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Carn.  Inst.  \\'  \sii.  Pub'n  6 


Saguaro  or  giant  cactus  (  Cereus.  giganteus)  near  Tucson,  Arizona.     About  40  feet 
high.     Birds  nest  in  the  cavities  of  the  trunk. 


Desert  Botanical  Laboratory 


OF   THE 


Carnegie  Institution 


FREDERICK  VERNON   COVILLE 


DANIEL  TREMBLY   MACDOUGAL 


WASHINGTON,  U.  S.  A.  : 
PUBLISHED    BY   THE   CARNEGIE   INSTITUTION 

November,   1903 


CARNEGIE   INSTITUTION   OF   WASHINGTON 
Publication  No.  6 


Pll»  Of 

til  ■•>  EM  Piiiriia  COMMir, 

LAICAtlll,  fK 


ANNOUNCEMENT. 

At  the  suggestion  of  Mr.  Frederick  V,  Coville,  botanist  of  the 
United  States  Department  of  Agriculture,  the  Advisory  Committee 
on  Botany  of  the  Carnegie  Institution,  recommended  the  establish- 
ment of  a  Desert  Botanical  Laboratory  in  the  arid  region  of  the  United 
States,  the  purpose  of  such  establishment  being  to  thoroughly  study 
the  relation  of  plants  to  an  arid  climate  and  to  substrata  of  unusual 
composition.  Mr.  Coville  and  Dr.  D.  T.  MacDougal,  v^^ho  were 
already  well  acquainted  with  the  arid  regions  of  the  United  States, 
were  requested  to  act  as  a  committee  of  inquiry  on  this  subject.  The 
results  of  their  inquiry  are  herewith  presented,  from  which  it  will  ap- 
pear that  a  site  for  a  botanical  laboratory  has  been  selected  near  Tuc- 
son, Arizona.  Dr.  W.  A.  Cannon,  of  the  New  York  Botanical  Gar- 
den, to  whom  a  grant  had  been  made  by  the  Carnegie  Institution,  in 
aid  of  research,  has  been  appointed  Resident  Investigator  in  charge 
of  the  Laboratory.  A  suitable  structure  has  been  erected,  and  the 
investigations  commence  in  the  autumn  of  1903. 

Daniel  C.  Oilman, 
President  of  the  Carnegie  Institution. 


63809 


CONTENTS. 

PAGE. 

Introduction i 

Laboratory  location  trip 2 

Itinerary  .    ,                    2 

Arid  region  of  western  Texas      3 

Sand  dunes  of  Cliihuahua 4 

Tularosa  desert .  5 

Analyses  of  sands 8 

Tucson  as  a  laboratory  site 12 

History 14 

Nogales       .        .    .  17 

Torres 17 

Guaymas ,19 

Colorado  desert 20 

Mohave  desert 22 

Grand  Canyon  of  the  Colorado 23 

Plant  life  in  North  American  deserts 23 

Meteorology .  i$ 

Tables 25 

Discussion 27 

Soil 29 

Historical 32 

Transpiration  and  temperatures 38 

Bibliography 46 


ILLUSTRATIONS. 

PLATE.  FACING  PAGE. 

I.    Giant  cactus  {Cereus  giganteus)  near  Tucson,  Arizona  (Frontispiece) 

II.    Tree  yucca  (  Yucca  radiosa)  in  the  Tularosa  desert,  New  Mexico   .  5 

III.  The  White  Sands,  Tularosa  desert 5 

IV.  Sand  column  in  the  White  Sands ...  6 

V.    In  the  White  Sands,  Tularosa  desert,  looking  northwest              .    .  7 

VI.    Water  hole  in  the  White  Sands 7 

VII.  Yucca  radiosa  growing  up  through  a  dune  thirty  feet  high      ...  7 

VIII.    Advancing  eastern  margin  of  the  White  Sands .    .  7 

IX.    Winter  vegetation  of  desert  plain  at  Tucson,  Arizona       12 

X.    Cat's  claw  tree  {Acacia  gfeggii)  n&ax  Tucson 12 

XI.    Tucson  mountain,  near  Tucson    ...                14 

XII.    Vegetation  on  Tucson  mountain,  near  Tucson                 14 

XIII.  Looking  westward  from  site  of  Laboratory 14 

XIV.  Yucca-like  vegetation  at  Nogales,  Arizona 17 

XV.   Vegetation  of  the  Sonera  desert  near  Torres,  Mexico         17 

XVI.    Guarequi  (/^e;'Z'///ea  5o«orae)  under  bushes,  near  Torres     ....  18 

XVII.    Tree.  ocotiWo  {Fouquieria  macdougalii)  near  Torres 18 

XVIII.    Papago  Indian  drinking  from  a  cactus  {Echinocactus  emoryi)     .    .  19 

XIX.    Yaki  Indian  family  and  house,  west  of  Torres 19 

XX.    Ollas  at  a  Yaqui  Indian  house  west  of  Torres 19 

XXI.    Desert  island,  Guaymas  bay,  Mexico  ...                   20 

XXII.    Cereus  pringlei  on  above  island 20 

XXIII.  Salt  valley,  Colorado  desert,  California 21 

XXIV.  Salt  encrusted  ground  near  Salton,  California ...  21 

XXV.    Group  of  palms,  Colorado  desert,  California    .    .            21 

XXVI.    Belt  of  palms,  Colorado  desert,  California 21 

XXVII.    Vegetation  in  the  Grand  Canyon,  Arizona 23 

XXVIII.    Bright  Angel  trail.  Grand  Canyon,  Arizona         , .23 

XXIX.    Alpine  desert  on  summit  of  San  Francisco  inountain,  Arizona  .    .  43 


PAGE. 

Fig.  I.  Rainfall  map  of  arid  regions  .    .  .    .  28 

Fig.  2.  Copy  of  map  of  American  deserts,  1835  .    .  32 

Fig- 3-  Copy  of  map  of  American  deserts,  1859 35 

Fig.  4.  Meteorological  data  from  San  Francisco  mountain,  Arizona  ...  44 


THE  DESERT  BOTANICAL  LABORATORY  OF  THE 
CARNEGIE  INSTITUTION. 

Introduction. 

Several  investigators,  in  Experiment  Stations  and  other  branches  of 
government  inquiry,  have  made  special  studies  of  the  relations  of 
plants  to  alkaline  and  other  soils.  They  have  also  observed  the  be- 
havior of  plants  in  arid  regions  under  the  influence  of  irrigation.  For 
the  most  part,  both  of  these  classes  of  studies  w^ere  concerned  with 
special  and  local  problems,  the  immediate  purpose  of  such  study  being 
to  obtain  information  for  the  use  of  the  agriculturist  and  horticulturist. 
Despite  this  limitation  they  clearly  showed  the  need  of  a  broader  and 
more  thorough  study  of  the  technical  and  general  aspects  of  the  rela- 
tion of  plants  to  dry  climates  and  to  substrata  of  unusual  composition. 
Special  mention  should  here  be  made  of  the  results  obtained  by  Messrs. 
Kearney  and  Cameron,  who  have  investigated  the  separate  and  the 
combined  effect  upon  plants  of  the  substances  usually  found  in  alka- 
line soils.  Other  important  papers  are  cited  in  the  accompanying 
bibliography,  pages  53  to  58. 

When  the  Carnegie  Institution  was  established,  Mr.  Coville  deter- 
mined to  present  to  it  a  plan  for  a  Desert  Botanical  Laboratory.  This 
long  cherished  project  was  an  outcome  of  his  work  in  the  Death  Val- 
ley Expedition,  in  189 1.  A  plan  was  accordingly  drawn  up  by  him 
and  presented  to  the  Institution's  advisory  committee  in  Botany.  This 
committee  considered  and  approved  it  because  it  promised  results  con- 
cerning the  fundamental  processes  of  protoplasm  as  important  as  any 
in  the  whole  realm  of  botany.  The  Board  of  Trustees  of  the  Institu- 
tion also  approved  it,  and  appropriated  $8,000  for  the  establishment  of 
such  a  laboratory  and  its  maintenance  for  one  year.  Messrs.  Coville 
and  MacDougal  were  appointed  by  the  Institution  as  an  Advisory 
Board  in  relation  to  the  matter.  This  Board  decided  to  place  the 
Laboratory  under  the  immediate  charge  of  a  resident  investigator,  who 
should  carry  on  researches  under  its  guidance,  and  should  be  respon- 
sible to  it  in  his  relations  to  the  Institution.  It  was  planned  to  begin 
a  few  inquiries  of  wide  scope  and  important  bearing  to  be  carried  on 
by  the  resident  investigator  until  decisive  results  were  obtained. 

Furthermore,  it  was  arranged  to  provide  such  an  equipment  as  would 

I 


N.   C.   State   College 


2  DESERT    BOTANICAL    LABORATORY 

enable  a  small  number  of  trained  investigators,  should  they  so  desire, 
to  utilize  the  opportunity  for  studying  those  questions  for  whose  solu- 
tion the  Laboratory  and  its  environment  are  especially  favorable.  Not 
the  least  important  part  of  the  duties  of  the  resident  investigator  wrill  be 
to  aid  visiting  botanists  and  others. 

The  Laboratory  Location  Trip. 

Each  member  of  the  Advisory  Board  had  visited,  during  the  pre- 
ceding twelve  years,  most  of  the  more  marked  desert  areas  of  the 
country.  Nevertheless,  it  was  deemed  profitable  to  make,  together,  a 
systematic  tour  of  these  deserts  in  order  to  gain  a  better  comparative 
knowledge  of  the  aspects  of  their  vegetation,  and  to  select  a  locality 
offering  the  greatest  advantages  and  facilities  for  the  proposed  work. 
Accordingly,  between  January  24  and  February  28,  1903,  they  made 
a  reconnaissance  of  the  region  along  the  Mexican  boundary.  As  the 
outcome  a  site  was  selected  on  a  small  mountain  near  Tucson,  Arizona, 
and  the  erection  of  a  laboratory  building,  according  to  plans  approved 
by  them,  was  begun.  The  organization  of  the  Laboratory  was  carried 
a  step  further  by  the  appointment  of  Dr.  W.  A.  Cannon  as  resident 
investigator.  He  at  once  undertook  the  preparation  of  the  bibliography 
of  desert  plants,  which  is  printed  in  this  report,  pages  46  to  58. 

As  no  publication  exists,  suitable  to  the  needs  of  the  botanist  who 
visits  our  western  deserts,  it  has  seemed  desirable  to  present  a  brief 
narrative  of  the  trip,  accompanied  by  illustrations  of  landscapes  show- 
ing characteristic  vegetation.  The  observations  were  necessarily  in- 
terrupted by  night  travel,  and  as  the  time  at  command  was  short,  only 
a  mere  skeleton  of  the  desert  flora  can  be  presented.  If,  however, 
this  shall  serve  to  convey  an  idea  of  the  diversity  of  the  several  lesser 
floras  of  which  the  whole  is  made  up,  and  of  the  wealth  of  material 
afforded  for  detailed  geographical  and  physiological  study,  the  chief 
purpose  of  this  portion  of  the  report  will  have  been  accomplished. 

itinerary. 

The  two  members  of  the  Board  having  met  at  Washington  left  that 
city  January  24,  1903,  and  arrived  at  El  Paso,  Texas,  on  the  morning 
of  January  28.  During  the  day  they  visited  the  sand  dunes  in  the 
Chihuahua  desert  between  Samalayuca  and  Los  Medanos,  Mexico, 
and  in  the  evening  took  the  train  for  Alamogordo,  New  Mexico. 
From  January  29  to  January  31  they  were  engaged  in  a  wagon  trip  to 
the  White  Sands  of  the  Tularosa  desert,  southwest  of  Alamogordo. 
On  February  i   they  returned  to  El  Paso  and  proceeded  by  rail   to 


ARID    REGION    OF    WESTERN    TEXAS  3 

Tucson,  Arizona.  Here  they  remained  February  2  and  3,  examining 
the  desert  flora  of  the  plain  and  adjacent  mountain  slopes.  On  Feb- 
ruary 4  they  proceeded  by  rail  to  Nogales,  on  the  boundary  line 
between  Arizona  and  Mexico,  where  they  stayed  February  5,  making 
observations  on  the  vegetation  in  that  vicinity.  On  the  morning  of 
February  6  they  arrived  by  rail  at  Torres,  Sonora,  Mexico.  February 
7  to  10  was  spent  on  a  saddle  trip  into  the  desert  west  of  Torres, 
toward  the  Gulf  of  California.  February  ii  a  journey  was  made  by 
rail  to  Guaymas  and  return  which  afforded  an  opportunity  to  observe 
both  the  desert  and  the  seacoast  flora  of  Guaymas  harbor.  February 
12  and  13  were  passed  on  the  desert  in  the  immediate  vicinity  of 
Torres.  On  February  14  the  Board  returned  to  Tucson  where  they 
remained  during  the  two  following  days.  On  the  morning  of  February 
17  they  arrived  by  rail  at  Salton,  in  the  Colorado  desert  of  southern 
California,  and  remained  during  the  day  examining  the  vegetation  of 
the  salt  and  alkali  lands.  On  the  morning  of  February  18  they  pro- 
ceeded to  Indio,  also  in  the  Colorado  desert,  and  in  the  afternoon  drove 
to  Thousand  Palm  canyon  and  return.  February  19  they  went  by 
rail  to  Los  Angeles  and  the  next  morning  took  a  train  east,  passing 
through  Cajon  pass  and  across  the  Mohave  desert,  arriving  on  the 
evening  of  February  21  at  the  Grand  Canyon  of  the  Colorado  river, 
in  Arizona.  February  22  and  23  were  spent  in  a  trip  to  the  river  by 
the  Bright  Angel  trail.  On  the  morning  of  February  24  they  left  the 
canyon  and  on  February  28  arrived  in  Washington. 

THE    ARID    REGION    OF    WESTERN    TEXAS. 

Eastern  Texas  has  the  characteristic  humid  subtropical  flora  of  the 
Gulf  region,  with  longleaf  pine  (^Pinus  palustris)^  cane  (^Arundi- 
narid)^  bald  cypress  {^Taxodium  dtsticktim) ^  and  their  associates,  but 
this  flora  gradually  merges  into  the  wholly  different  one  of  arid 
western  Texas.  Beginning  east  of  San  Antonio  the  ground  is  covered 
with  an  open  growth  of  mesquite  trees  {Prosopis)^  10  to  20  feet 
high,  resembling  a  vast  peach  orchard.  Scattered  through  it  are  larger 
trees,  some  deciduous,  others  evergreen  oaks.  The  mesquites  them- 
selves are  nearly  leafless  in  late  winter  and  are  much  infested  with  a 
mistletoe.  Scattered  among  them  are  various  shrubs  4  to  8  feet 
high,  and  as  the  most  conspicuous  feature  of  the  undergrowth  a 
prickly  pear  with  large  flat  orbicular  vertical  joints,  the  whole  plant 
rising  i  to  3  feet  from  the  ground.  Another  occasional  feature  of  the 
undergrowth  is  a  small  Tucca  with  long  and  broad  leaves,  commonly 
without  a  trunk  but  occasionally  reaching  a  height  of  6  to  8  feet. 
Some  of  the  oaks  have  their  branches  clothed  with  a  gray  epiphyte 


4  DESERT    BOTANICAL    LABORATORY 

{Tillandsia) .  Between  Sabinal  and  Uvalde  occur  areas  on  the 
higher,  more  sterile  parts  of  the  plain,  over  which  the  mesquite  and 
oaks  are  wanting,  the  undergrowth,  however,  remaining.  These 
areas  often  contain  a  growth  of  an  Acacia  2  to  3  feet  high  with  dark 
yellowish-green  persistent  foliage,  the  whole  plant  suggesting  the 
creosote  bush  of  the  more  western  desert. 

Between  Del  Rio  and  Devils  River  a  change  in  the  flora  takes  place, 
the  sotol  (^Dasylirion)  becoming  the  most  conspicuous  feature  of  the 
upland  vegetation,  with  a  broad  leaved  Tucca  having  a  trunk  i  to  6 
feet  high,  a  shorter  leaved  grayer  plant  than  the  one  about  San  Antonio. 
The  Acacia  mentioned  earlier  and  various  shrubs,  chiefly  gray  leaved 
and  spinose,  are  also  abundant,  while  the  mesquite  is  small  and  con- 
fined chiefly  to  the  ravines.  A  lechuguilla  {Agave)  occurs  on  rocky 
slopes  and  thin  soils,  and  a  coral  bean  {Sophora  secundijlora),  with 
its  shining,  bright  green  leaves,  in  the  canyons. 

Between  Shumla  and  Dorso  the  ocotillo  {Fouquieria  splendens)  and 
the  creosote  bush  ( Covillea  tridentata)  appear,  interspersed  with 
the  large  yucca,  the  lechuguilla  growing  in  abundance  on  thin  rocky 
soils  with  acacia,  and  the  mesquite  and  a  small  juniper  growing  in  the 
washes.  The  area  is  characterized  also  by  a  second  smaller  species 
of  Opuntia^  in  addition  to  the  larger  one  earlier  mentioned,  and  by  an 
Ephedra^  probably  E.  antisyphilitica .  The  ocotillo  disappears  at 
an  elevation  of  about  2,000  feet  as  the  plateau  west  of  the  Pecos  is 
reached. 

THE    SAND    DUNES    OF    CHIHUAHUA. 

South  of  El  Paso  and  crossed  by  the  old  traders'  trail  from  Santa 
Fe  to  the  city  of  Chihuahua  is  a  long  stretch  of  sand  dunes  which  we 
had  determined  to  examine  ;  these  were  familiar  to  the  early  travelers 
but  are  almost  unknown  to  the  botanists  of  today.  Taking  a  Mexican 
Central  train  at  Juarez  we  were  put  off,  through  the  courtesy  of  the 
railroad  officials,  among  the  sand  dunes,  about  six  miles  south  of  the 
station  of  Samalayuca.  This  station  is  eighteen  miles  from  Juarez  and 
one  mile  north  of  Los  Medanos. 

The  dunes  where  the  railroad  crosses  them  are  about  forty  feet  high, 
with  scant  winter  vegetation  consisting  of  a  few  w^oody  plants,  princi- 
pally a  labiate  bush  {Poliomintha  incana)^  an  Artemisia^  a  Chryso- 
thamnus^  a  Tucca  {Tucca  radiosa)^  and  a  suffrutescent  Senecio. 
Two  perennial  grasses,  an  Andropogon  and  a  Sporobolus  with  a  spike- 
like panicle  {Sporobolus  cryptandrus) ^  are  of  frequent  occurrence  as 
are  the  remnants  of  many  annual  plants.  The  Tucca  takes  an  impor- 
tant part  in  binding  the  sands  ;  roots  were  seen  extending  in  a  nearly 
horizontal  direction  forty  feet  from  the  plant. 


Carn.  Inst.  Wash.  Pub'n  6 


Plate  II 


Tree  yucca  (  Yucca  radiosa)  in  the  Tularosa  Desert,  New  Mexico.     The   large  plant. 

which  is  in  fruit,  has  lost  some  of  its  lower  leaves  by  the  nibbling  and  rubbhig  of 

cattle.     The  two  small  plants  are  younger  specimens  of  the  same  species. " 


Carx.  Inst.  Wash.  Prii'x  6 


Plate  III 


C/3     o 


Z    5 

~  o 


THE    TULAROSA    DESERT  5 

From  the  dunes  toward  Samalayuca  the  valley  bottom  has  a  vegeta- 
tion of  mesquite  mixed  with  Zizypkus,  Koeberlinia  spinosa,  and  Atri- 
plex  canescens.  An  annual  Croton  forms  a  thick  spindle  shaped 
tumble  weed  adapted  for  rolling  only  along  one  axis. 

The  highest  part  of  the  dunes  is  not  crossed  by  the  railroad  but  lies 
east  and  southeast  from  Samalayuca  about  five  miles  and  apparently 
rises  200  to  300  feet  from  the  plain. 

About  nine  pounds  of  the  material  of  which  the  dunes  were  com- 
posed was  collected  by  removing  a  thin  surface  layer  and  then  placing 
in  a  cloth  waterproof  bag.  This  material  was  forwarded  to  Dr.  W. 
J.  Gies,  consulting  chemist  to  the  New  York  Botanical  Garden  with 
the  request  for  an  analysis.  Dr.  Gies'  report  is  printed  on  pages  10  and 
II  of  this  pamphlet. 

THE    TULAROSA    DESERT. 

Starting  westward  from  Alamogordo,  New  Mexico,  across  the 
Tularosa  desert,  one  first  enters  a  region  characterized  by  low 
mesquites,  commonly  3  to  6  feet  high,  with  an  abundance  of  Atriplex 
canescens  and  Koeberlinia  spinosa.  That  the  soil  is  alkaline  is  in- 
dicated by  a  surface  deposit  along  an  irrigating  ditch.  The  ground 
bears  also  an  abundance  of  a  suffrutescent  Suaeda^  a  bunch  Sporobolus 
with  expanded  panicles,  and  occasional  specimens  of  a  Lyciuni.  In 
low  spots  and  along  the  margins  of  clay  bottomed  washes,  an  incrus- 
tation of  alkali  appears,  accompanied  by  Allenrolfea  occidefitalis. 
In  this  area  water  is  commonly  found  in  wells  at  a  depth  of  50  to  70 
feet.  Toward  the  middle  of  the  valley  the  mesquite  disappears,  and 
the  principal  bush  vegetation  is  Atriplex  canescens^  with  a  great  deal 
of  the  Sporobolus  and  areas  in  which  Tucca  radiosa  (Plate  II),  or 
Opuntia  arborescens^  or  another  Opuntia^  conspicuous  at  this  season 
by  its  scarlet  fruit,  are  abundant.  The  wagon  road  in  this  part  of 
the  valley  often  strikes  at  the  depth  of  a  foot  the  so  called  caliche  rock, 
a  sort  of  hardpan.  Ground  water  is  presumably  to  be  found  only  at  a 
great  depth. 

Our  principal  object  on  this  trip  into  the  Tularosa  desert  was  to 
examine  the  flora  of  a  remarkable  area  of  drifting  sand  it  contains, 
known  as  the  White  Sands,  composed  not  of  silica  but  of  gypsum,  and 
estimated  to  cover  an  area  of  10  by  40  square  miles  (Plate  III) .  These 
sands  are  most  easily  reached  at  a  point  about  20  miles  southwest  of 
Alamogordo.  Here  there  are  some  water  holes  where  horses  when 
forced  by  continued  thirst  can  be  watered  with  safety.  Water  for  men, 
however,  must  be  carried  from  Alamogordo. 

Two  principal  plant  formations  occur  in  the  bottoms  and  the  dunes 


6  DESERT    BOTANICAL    LABORATORY 

of  the  White  Sands.  The  bottoms  occur  at  nearly  the  same  level  as 
the  surface  of  the  plain  surrounding  the  sands,  the  dunes  are  irregular 
heaps  and  ridges  of  white  gypsum  sand,  rising  to  a  maximum  height 
estimated  at  60  feet.  When  moist  the  sand  is  of  a  slightly  yellowish 
or  buff  color,  when  dry  almost  pure  white.  When  taken  in  the  hand 
it  has  not  the  sparkling  effect  of  silicious  sand,  but  its  grains  are  dull 
even  in  sunlight.  As  compared  with  silicious  sand  it  may  be  likened 
to  corn  meal,  the  other  to  granulated  sugar.  The  separate  grains  can 
be  rubbed  between  the  fingers  to  a  fine  white  powder.  Except  on 
steep  slopes  the  dunes  of  the  White  Sands  form  an  excellent  surface  for 
walking,  comparable  in  hardness  with  a  sandy  seabeach  wet  by  an 
outgoing  tide.  These  hard  surfaces  are  covered  everywhere  with  rip- 
ple marks  caused  by  the  wind. 

The  most  characteristic  plant  of  the  dunes  is  the  threeleaf  sumac 
{Rhus  trilobata)^  which  occurs  in  the  form  of  single  hemispherical 
bushes  4  to  8  feet  high,  the  lower  branches  hugging  the  sand.  The 
plant  grows  vigorously,  the  trunk  at  or  beneath  the  surface  often 
reaching  a  diameter  of  3  inches.  The  binding  and  protecting  effect 
of  this  bush  is  often  shown  in  a  striking  manner  when  in  the  cutting 
down  of  an  older  dune  by  the  wind  a  column  of  sand  may  be  left  pro- 
tected above  from  the  rain  by  the  close  covering  of  the  branches  and 
leaves,  and  the  sand  in  the  column  itself  bound  together  by  the  long 
penetrating  roots.  An  incrustation,  apparently  of  gypsum,  is  often 
found  on  dead  roots.  One  of  these  columns  was  about  15  feet  high 
fi-om  its  base  to  the  summit  of  the  protecting  bush  and  about  8  feet 
in  diameter  at  the  base  (Plate  IV) .  A  curious  fact  brought  out  in  the 
denudation  of  the  underground  trunks  of  this  plant  by  the  shifting  of 
the  dunes  is  the  abundant  exudation  of  a  pale  amber  gum  with  the  char- 
acteristic aroma  of  the  crushed  twigs.  This,  mixing  with  the  sand, 
forms  hard  honeycombed  masses  sometimes  three  inches  in  diameter. 

Other  characteristic  woody  plants  of  the  dunes  are  Atriplex  canes- 
cens^  two  species  of  Chiysothamnus ^  and  Yucca  radiosa.  The  under- 
ground trunks  of  the  Atriplex  often  attain  a  diameter  of  four  inches, 
those  of  the  Yucca  six  inches.  A  marked  peculiarity  of  the  White 
Sands  is  that  a  cottonwood  is  occasionally  found  in  the  lower  dunes, 
reaching  a  foot  in  diameter  but  seldom  more  than  fifteen  feet  in  height ; 
yet  at  the  same  time  not  a  mesquite  was  seen.  The  mesquite  is  a  tree 
requiring  less  moisture  than  the  cottonwood.  Apparently  the  presence 
of  an  excess  of  lime  is  prejudicial  to  the  growth  of  the  mesquite. 

The  bottoms  among  the  dunes  have  a  dense  vegetation  as  compared 
with  that  of  the  dunes  themselves.     It  is  characterized  especially  by  the 


Carn.  Inst.  Wash.  Pik'n  6 


Pr.ATK  I\- 


Carn.  Inst.  Wash.  Pl  b'n  6 


Platk  V 


;^   P 


H  -5 
^'"  c 


Carn.  Inst.  Wash.  Plisn  6 


Plate  VI 


I? 


X!     O 


Carn.  Inst.  Wash.  Pib'n  6 


Plate  VII 


y'«<"  nnhos,r  growing  up  through  a  dune  30  feel  high,  White  Sands.  New  Mexico 
.\  tew  of  the  upper  circles  of  leaf  bases  can  be  seen  in  the  picture. 


C\RN.  Inst.  Wash.  Pib'n  6 


Plate  VIII 


— ■    1) 


o    p 


H    ^ 


k5    -O 


c    cs 


THE    TULAROSA    DESERT  7 

presence  of  a  grama  grass  {Bouteloud)  forming  almost  a  turf,  and 
by  frequent  clumps  of  an  Ephedra^  of  a  grayish  purple  color  at 
this  season  and  with  3-scaled  nodes  (Plate  V).  These  bottoms  usually 
show  no  sign  of  moisture,  but  in  two  places  we  found  water  holes,  the 
water  so  alkaline  that  the  horses  would  not  drink  it  at  the  end  of  their 
first  day's  drive.  About  both  holes  occurred  salt  grass  (^Distichlis 
spicata)  and  wire  grass  {Jtmcus  balticus)^  both  of  them  character- 
istic of  moist  alkaline  soils  (Plate  VI). 

In  addition  to  their  woody  vegetation  the  White  Sands  appear  to 
have  an  abundant  herbaceous  vegetation  which  would  well  repay  care- 
ful systematic  and  ecological  study.  The  area  they  cover  is  large, 
probably  400  square  miles  or  more,  the  physical  and  chemical  proper- 
ties of  the  soil  are  very  unusual,  and  no  botanist  has  yet  thoroughly 
studied  the  vegetation. 

The  relation  of  Yucca  radiosa  to  the  sand  dunes  is  unusually  inter- 
esting. A  group  of  four  small  yucca  plants  standing  about  three  feet 
high  to  the  tip  of  the  highest  leaf,  was  found  upon  the  summit  ridge  of 
a  thirty-foot  dune.  We  dug  the  trunk  out  to  a  depth  of  14  feet.  All 
four  plants  were  from  branches  of  the  same  trunk,  the  lowest  branch 
arising  about  16  feet  from  the  base  of  the  dune  ;  the  main  trunk  and  the 
branches  bore  marks  of  rosettes  of  leaves  at  intervals  all  the  way  to 
the  lowest  point  reached.  The  trunk  was  thicker  here,  about  4  inches, 
than  at  any  point  above.  The  strata  in  the  cut  showed  that  the  yucca 
once  stood  on  the  front  slope  of  the  dune.  The  trunk  sloped  in  the 
direction  in  which  the  dune  was  moving.  In  the  plain  in  front  of  the 
dunes  were  occasional  low  plants  of  the  same  species  of  yucca.  Con- 
sidering all  the  evidence  the  conclusion  is  irresistible  that  the  yucca 
originally  grew  on  the  plain,  was  engulfed  by  the  sand,  and  gradually 
grew  through  each  successive  layer  of  sand  that  drifted  over  it,  until 
the  summit  of  the  dune  was  reached.  In  the  vicinity,  at  the  rear  of 
the  dune,  were  other  long  trunks  partly  denuded  by  the  passing  of 
the  dune  (Plate  VII) . 

A  gentleman,  familiar  with  the  White  Sands  for  twenty  years,  told 
us  that  in  that  time  they  had  advanced  eastward  at  one  point,  the  one 
of  greatest  activity,  about  half  a  mile.  A  road  traversing  the  plain  in  a 
north-south  direction  close  to  the  eastern  front  of  the  sand  showed  fre- 
quent changes  necessitated  by  the  advance  of  the  dune  (Plate  VIII). 

A  section  from  the  base  of  the  Sacramento  mountains  southwest 
through  Alamogordo  into  the  White  Sands,  shows  four  belts  :  ( i )  the 
delta  slopes  from  the  mountain  canyons,  characterized  by  a  nearly  pure 
growth  of  creosote  bush  (^Covillea  tridciitata)^  the  soil  usually  grav- 


8  DESERT    BOTANICAL    LABORATORY 

elly  and  probably  washed  nearly  free  from  alkali;  (2)  the  mesquite 
area  already  described;  (3)  the  Atriplex  area  also  already  described, 
and  (4)  the  White  Sands. 

The  Tularosa  desert  as  traversed  by  the  railroad  from  Alamogordo 
south  to  El  Paso  has  a  red  and  apparently  mellow  soil,  the  most  char- 
acteristic plant  of  which  is  Yucca  radiosa^  sometimes  associated  over 
large  areas  with  grass,  but  often  associated  with  low  mesquites,  the 
latter  in  some  spots  gathering  large  hummocks  of  earth  from  drifting 
dust,  out  of  which  the  twigs  of  the  mesquites  project.  A  large  Ephe- 
dra is  also  a  frequent  associate  of  the  mesquite  and  yucca.  The  rail- 
road traverses  only  a  little  of  the  creosote  bush  foot  slopes  of  the  moun- 
tains. 

Analyses  of  Sands. — The  following  report  on  the  gypsum  sand  from 
the  White  Sands  of  the  Tularosa  desert  and  on  sand  from  the  Chihua- 
huan  desert  has  been  received  from  Dr.  William  J.  Gies  : 

Gentlemen  :  I  present  herewith  the  results  of  my  chemical  analyses  of  the  two 
samples  of  sand  expressed  by  you  to  me  from  Tucson,  Arizona,  on  February  16 
and  received  by  me  on  February  24  : 

SAMPLE    I.       locality:    TULAROSA  DESERT,  NEW  MEXICO.^ 

General  Descrij)tio7i. —  Color  white  to  delicate  cream,  with  occasional  very 
minute  black  particles.  There  were  also  a  few  reddish  and  yellowish-red  grains. 
Now  and  then  red  specks  could  be  detected  in  the  white  grains.  Glassy  grains 
of  silica  were  present.  Nearly  all  the  grains  were  very  small,  about  the  size  of 
those  in  ordinary  sea  sand.  A  few  larger  masses  were  made  up  of  many  of  the 
small  grains  cemented  or  fused  together.  These  masses  were  more  cream 
colored  "than  the  small  grains,  some  contained  a  dark  nucleus.  They  varied  in 
size  from  such  as  were  only  three  or  four  times  the  bulk  of  the  uniformly 
small  grains  to  a  few  which  were  nearly  as  large  as  a  pea.  No  special  crystalline 
qualities  were  observed  in  any  sample  of  the  sand.  The  grains  were  angular, 
or  rounded  by  erosion.  Fragments  of  elytra  of  beetles  were  detected  and  oc- 
casional pieces  of  hair,  and  small  splinters,  were  also  seen. 

Before  subjecting  the  sand  to  analysis  it  was  passed  through  a  copper  sieve 
the  meshes  of  which  were  just  large  enough  to  permit  the  passage  of  the  typical 
and  uniformly-sized  grains.  Only  a  few  grams  of  material  consisting  of  the 
larger  fused  particles,  elytra  of  beetles,  hair,  etc.,  was  separated  in  this  way  from 
four  kilos  of  the  sand  as  received.  All  of  this  material  was  regarded  as  extraneous 
matter,  and  only  the  main  bulk  of  the  sand  was  analyzed  quantitatively. 

Qualitative  Data. — The  sand  dissolved  readily  in  water  and  in  dilute  acids, 
leaving  only  a  slight  residue  of  silicious  matter.  The  black  particles  in  the  sand 
seemed  to  be  entirely  insoluble  in  these  media.  The  aqueous  solution  was  neu- 
tral to  litmus.  The  hydrochloric  acid  solution  was  slightly  yellowish  in  color, 
due  doubtless  to  the  presence  of  iron.  On  diluting  the  hot  concentrated  sul- 
phuric acid  solution,  crystals  of  calcium  sulphate  quickly  separated.  On  ignit- 
ing the  sand  it  immediately  blanched,  and  abundance  of  water  was  evolved,  but 
the  sand  did  not  fuse,  even   in  platinum,  over  a  blowpipe.     Extraction  of  the 


ANALYSES    OF    SANDS  9 

ignited  sand  in  water  gave  a  solution  slightly  alkaline  in  reaction.  Only  a  minute 
trace  of  carbonic  acid  gas  could  be  produced  from  the  sand  on  ignition,  a  fact 
showing  that  practically  no  organic  matter  is  contained  in  it.  Such  organic 
matter  as  was  actually  present  in  the  few  particles  separated  from  the  sand  con- 
sists, as  already  stated,  of  the  fragments  of  insects,  e.\creta  of  animals,  etc.,  and 
is  too  slight  in  quantity  to  have  much  significance  as  nutrient  material  for  plants. 

On  drying  a  sample  of  the  sand,  in  an  air  bath  at  lOo"  C,  it  soon  became 
translucent  and  finally  snow  white.  The  grains  retained  their  original  shape. 
Water  of  crystallization  was  eliminated  in  abundance.  The  sand  contains  traces 
of  sodium  phosphate  and  chloride.  The  larger  particles  removed  with  the  sieve 
contained  a  more  decided  quantity  of  chlorine,  0.7  to  0.9  per  cent. 
Quantitative  Analysis. 

Preliminary  Data. 

A.  Sand  dried  in  an  air  bath  at  30°-35°  C.  : 

(a)  On  drying  to  constant  weight  in  an  air  bath  at  iio°-i20°  C.  the  quantity 
of  water  eliminated  was  19.9  per  cent. 

(d)  On  drying  to  constant  weight  in  an  air  bath  at  50°-6o°  C.  the  weight  of 
the  substance  remained  the  same. 

(c)  On  continuous  percolation  at  room  temperature  of  small  quantities  of  dis- 
tilled water  at  a  time  over  the  sand,  until  about  100  parts  water  to  one  of  sand 
was  used,  79.9  per  cent,  of  the  sand  was  dissolved  and  only  20.1  per  cent,  of  it 
remained  as  residue.  The  latter  was  still  dissolving  when  the  experiment  was 
discontinued  and  further  percolation  would  have  reduced  the  amount  of  residue 
(see  under  B.,  [d)  4  below). 

(d)  On  continuous  percolation,  as  above,  with  distilled  water  at  30°  C.  the 
dissolved  matter  amounted  to  87.1  per  cent.,  and  the  residue  to  only  12.9  per 
cent.  Further  percolation  would  have  decreased  the  weight  of  the  residue  (see 
under  B,  {d)  3  below). 

B.  Sand  dried  in  an  air  bath  at  iio''-i20^  C. 

(a)  On  ignition  in  a  platinum  crucible  over  a  blowpipe  the  loss  of  weight  was 
I.I  per  cent. 

{&)  On,treatment  for  three  hours  with  about  i  liter  of  hot  acids,  hot  water  or 
cold  water  per  gram  of  substance  the  following  data  were  obtained  : 


Substance  Dissolved. 


Residue. 


One  part  HCl  and  three  parts  HjO 

Two  parts  HNO3  ^"^  two  parts  H,0.. 

Boiling  HjO 

Cold  HjO  (X5°C.) 


Per  cent. 
97.4 
97.8 
94-3^ 
96.4 


Per  cent . 
2.6 
2.2 

5-7 
3-6 


Some  General  Deductions.  — The  analytic  results  set  forth  in  the  above  table 
and  in  that  on  the  following  page  show  that  the  sand  is  mainly  composed  of 
grains  of  calcium  sulphate  derived  from  crystalline  gypsum.  Silica  and  also 
silicate  of  iron  and  aluminum  are  present  in  small  amounts.  Insignificant  quan- 
tities of  soluble  substances  such  as  chloride  (probably  of  calcium)  may  also 
be  detected. 

The  sand  is  free  from  nitrogenous  matter  except  such  minute  "amounts  of 
animal  ddbris  and  excreta  as  have  already  been  referred  to. 

'Calcium  sulphate  is  more  soluble  in  cold  than  in  hot  water. 


DESERT    BOTANICAL    LABORATORY 


Percentage  Composition.     Sand  dried  at  30°-35°C.  and  at  iio°-i20°C. 


CaO  .... 

SO3 

SiOj  .... 
Al,03  ) 
Fe,03  /  • 

H,0 

Traces : 
Calcium 
Calcium 


O,  CI,  Na,  PO<  (by  difference) 

sulphate,  CaSO^.aHjO 

sulphate,  anhydrous 


Per  cent. 

30-4 

44-5 

2.8 

0.4 


IL 


Per  cent. 
31.2 

43-9 
2.6 

0.4 

20.8 


Average. 


Per  cent. 

30.8 

44.2 

2.7 

0.4 

20.8 

95-8 
750 


Average. 
Per  cent. 

38.5 

55-1 
3-4 

0.5 
I.I 
1.4 

93-6 


It  is  very  evident  that  the  sand  readily  dissolves  in  w^ater.  Every  rain,  no 
doubt,  dissolves  some  of  it  and  the  waters  in  the  district  from  which  the  sand 
was  obtained  must  be  heavily  charged,  probably  to  the  saturation  point,  with 
gypsum.  On  the  evaporation  of  such  water,  in  the  sand  or  in  pools,  calcium 
sulphate  is  again  rapidly  deposited. 

SAMPLE    II.       LOCALITY  :    SAMALAYUCA,    CHIHUAHUA,  MEXICO. 

General  Description.  — A  composite  sand,  yellowish  to  light  brown  in  general 
appearance.  No  crystals  were  detectable  in  it.  The  grains  were  of  irregular 
shape,  but  of  fairly  uniform  size.  None  were  any  larger  than  the  small  uni- 
formly sized  ones  of  Sample  I.  The  grains  were  angular,  with  the  edges  showing 
the  effects  of  erosion.  Glassy  and  brownish  grains  predominated.  Others 
with  the  following  colors  were  to  be  seen  :  Amethyst,  dull  white,  dirty  yellow, 
purple,  black  and  red. 

All  of  this  sand  passed  readily  through  the  sieve  used  on  Sample  I.  No  ex- 
traneous matter  was  found  in  It. 

Qualitative  Data.  —  The  sand  was  very  resistant  to  the  solvent  action  of 
water,  alkalies  and  acids,  scarcely  anything  dissolving  in  these  fluids,  hot  or 
cold.  The  colored  grains  were  somewhat  reduced  in  number  after  treatment 
with  acid,  the  solution  in  hydrochloric  acid  having  a  yellowish  tinge.  The 
sand  fused  with  sodium  carbonate  with  great  difficulty.  The  fused  mass  was 
bluish-gray  in  color.  On  ignition  the  sand  lost  only  a  slight  amount  of  water. 
It  became  pink  and  yellowish-red  in  places  but  did  not  fuse,  even  in  platinum 
over  a  blowpipe.  Carbonic  acid  gas  could  not  be  obtained  from  it  on  ignition, 
so  that  the  sand  is  obviously  entirely  free  of  organic  matter.  On  drying  at 
iio°-i2o°  C.  no  change  in  appearance  occurred.  This  sample  contained  also 
minute  amounts  of  calcium,  sodium,  fluoride,  sulphate,  phosphate,  titanate. 
Quantitative  Analysis. 

Preliminary  Data. 

A.  Sand  dried  in  an  air  bath  at  30°-35°  C  : 

(a)  On  drying  to  constant  weight  in  an  air  bath  at  50°-6o°  C.  the  quantityrof 
water  eliminated  was  o.i  i  per  cent. 

{b)  On  drying  to  constant  weight  in  an  air  bath  at  iio°-i20°  C.  the  quantity 
of  water  eliminated  was  0.19  per  cent. 

B.  Sand  dried  in  an  air  bath  at  iio°-i20°  C. : 

(«)  On  ignition  in  platinum  over  a  blowpipe  the  quantity  of  water  elimi- 
nated was  0.5  per  cent. 


ANALYSES    OF    SANDS 


{l>)  On  treatment  for  three  hours  with  about  lOO  parts  of  hot  acids,  hot  water, 
or  cold  water  per  unit  of  substance  the  following  data  were  obtained  : 


Substance  Dissolved. 


Residue. 


One  part  HCl  and  three  parts  HjO. 

Two  parts  HNOj  two  parts  HjO 

Boiling  HjO 

Cold  HjO  (i5°C.) 


Percent. 
30 
2.6 
05 
06 


Per  cent. 
97.0 
97-4 
99-5 
99-4 


(c)  In  a  percolation  experiment  similar  to  those  on   Sample  I,  only  0.4  per 
cent,  of  the  substance  dissolved,  99.6  per  cent,  remaining  as  residue. 
Percentage  Composition.  —  Sand  dried  at  iio°-i20°  C. 


Average. 


SiO, 

Al.Os  \ 

Fe,03  ; 

Water 

O  in  silicate,  plus  traces,  Ca,  Fl,  SO^,  etc. 
Silica  and  insoluble  silicate,  not  less  than. 


Per  cent. 

85.9 

81 

0.6 


Per  cent. 
86.1 

8.3 
0.4 


Per  cent. 
86.0 

8.2 

0.5 

5.3 

95.0 


General  Conclusio7is.  —  This  sand  consists  chiefly  of  silica  and  of  insoluble 
silicates  of  iron  and  aluminum.  The  results  of  the  extraction  experiments,  in 
which  relatively  large  amounts  of  acid,  alkali,  and  water  affected  it  very  little, 
show  that  the  sand  is  one  of  the  most  insoluble  and  resistant  varieties,  and  that 
it  is  not  rapidly  altered  by  weathering  influences. 

COMPARATIVE    COMPOSITION,    SAMPLES    I    AND    II. 

Direct  comparison  of  the  results  for  composition  of  the  two  sands  is  made  in 
the  appended  summary  of  average  analytic  data  for  substance  dried  to  constant 
weight  at  iio°-i20°  C.  : 

Sand  dried  at  iio°-i20°  C. 


CaO. 
SO,. 
SiOj, 
AI2O. 
Fe.  " 
H 


I2O3   \ 
,0 


O  in  silicate  and  traces  of  other  elements  (by  difference). 

Chief  constituents  :     Calcium   sulphate , 

Silica  and  silicates , 


Sample  ] 


Per  cent. 

38.5 

55-1 

3-4 

0.5 
I.I 
1.4 
936 
3-9+ 


Sample  II. 


Per  cent, 
trace 
trace 
86.0 

8.2 

05 
5.3 


94.2+ 


Sample  I,  from  Tularosa  desert,  consists  mainly  of  gypsum. 
Sample  II,  from  Samalayuca,  is  almost  entirely  silicious. 

Respectfully  submitted, 

William  J.  Gies. 

\^est  of  El  Paso,  within  the  valley  of  the  Rio  Grande  the  character- 
istic vegetation,  above  the  moist  bottom,  is  creosote  bush,  with  some 


12  DESERT  BOTANICAL  LABORATORY 

ocotillo  and  lechuguilla  on  rocky  places.     The  soil  under  the  creosote 
bush  is  almost  always  gravelly. 

As  the  road  rises,  near  the  station  of  Strauss,  to  the  plateau  and 
crosses  it  westward  at  an  elevation  of  a  little  more  than  4,000  feet,  the 
same  flora  appears  as  that  of  the  Tularosa  desert;  mesquite,  Tucca 
radiosa^  and  grass,  or  either  of  these  plants  alone  with  the  grass,  and 
Ephedra  a  frequent  accompaniment.  Creosote  bush  occurs  only  oc- 
casionally and  on  gravelly  slopes  near  desert  hills. 

TUCSON    AS    A    LABORATORY    SITE. 

The  woody  vegetation  of  the  desert  in  the  vicinity  of  Tucson  con- 
sists chiefly  of  creosote  bush  (  Covillea  tridentatd)  interspersed  with 
several  species  of  Opuntia^  most  of  them  with  cylindrical  stems  (Plate 
IX),  and  occasional  plants  of  joint  pine  {Ephedra  triftirca^  and 
barrel  cactus  {Echinocactus),  w^ith  an  abundance  of  mesquite  {Pro- 
sopis^  and  cat's  claw  {Acacia  greggii)  (Plate  X)  in  the  lower  drain- 
age areas.  Upon  the  foothills  occur  in  addition  the  giant  cereus(  Cereus 
giga7iteus^  see  frontispiece),  two  species  of  palo  verde  {Parkinsonia 
microphylla  ixnd  P.  torrey ana)  ^ocoiiWo  {Fouquieria  splendens)^  two 
species  of  Lycluni  and  many  other  woody  plants.  This  is  of  course  in 
addition  to  a  great  variety  of  annual  vegetation  which  may  spring  up 
between  the  sparse  shrubs  after  any  drenching  rain,  particularly  the 
repeated  slow  rains  of  winter. 

In  recommending  a  site  for  the  Laboratory  the  Board  kept  in  mind 
four  principal  requirements  : 

1 .  A  distinctly  desert  climate  and  flora. 

2.  A  flora  as  rich  and  varied  as  possible,  while  still  of  a  distinctly 
desert  character. 

3.  Ready  accessibility. 

4.  Habitability. 

Much  of  the  arid  region  of  the  western  United  States  is  only  par- 
tially or  relatively  arid  and  does  not  therefore  contain  those  pronounced 
types  of  drouth  resistant  vegetation  which  it  is  the  first  object  of  the 
Laboratory  to  investigate.  Such  semi-desert  areas  are  the  western  por- 
tions of  Kansas  and  Nebraska,  and  the  intramontane  valleys  of  south- 
ern California.  Another  sort  of  location,  to  be  avoided  for  a  like 
reason,  was  a  desert  which  was  likely  to  be  reclaimed  by  irrigation, 
such  as  that  about  Phoenix,  Arizona.  The  desert  character  of  a  small 
area,  even  though  carefully  reserved,  might  be  seriously  modified  by 
seepage  or  other  changes  following  irrigation  development  in  the 
vicinity. 


Carn.  Inst    Wash.  Puh'n  6 


Plate  IX 


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Carn.  Inst.  Wash.  Pu»"n  d 


Plate  X 


TUCSON    AS    A    LABORATORY    SITE  I3 

Some  of  our  deserts,  such  as  the  Mohave,  the  Colorado,  and  the 
lower  part  of  the  Gila,  are  of  such  extreme  aridity  that  only  a  small 
number  of  vegetative  types  occur  in  them.  The  same  paucity  of  vege- 
tative types  is  usually  characteristic  of  any  flat  area  of  desert  as  distin- 
guished from  a  foothill,  canyon,  or  mountain  area,  a  broken  and  rocky 
soil  giving  a  wider  range  of  temperature  and  moisture  conditions  of 
both  soil  and  air,  and  furnishing  lodgment  for  a  greater  variety  of 
plants.  The  yucca  plains  of  the  Tularosa  desert  in  New  Mexico  and 
the  sage  plains  along  the  Snake  and  Columbia  rivers  in  Idaho,  Wash- 
ington, and  Oregon  are  examples  of  deserts  in  which  a  pronounced 
paucity  of  woody  species  is  correlated  not  with  extreme  conditions  of 
aridity  but  with  flatness  of  surface. 

The  members  of  the  Board  are  acquainted  with  several  charming 
situations  in  the  mountains  of  the  desert,  remote  from  civilization,  rich 
and  remarkable  in  their  flora,  furnished  with  an  abundance  of  pure 
never  failing  water,  and  altogether  delightful  in  their  surroundings. 
Such  situations  are  often  chosen  for  army  posts  and  they  are  and  will 
always  remain  treasure  spots  for  the  camping  naturalist.  For  the  pur- 
pose of  a  laboratory,  however,  they  are  objectionable  for  several  rea- 
sons. Such  a  situation  involves  first  of  all  the  maintenance  of  a  hotel 
or  its  equivalent,  a  feature  that  would  tend  to  exhaust  the  financial  and 
mental  resources  of  the  management  of  a  laboratory.  Furthermore, 
severe  isolation  for  long  periods  would  doubtless  have  a  depressing 
instead  of  an  exhilarating  effect  on  some  research  workers,  and  the 
solicitude  of  friends  and  relatives  would  doubtless  in  some  cases  be  a 
bar  to  residence  at  such  a  place. 

The  conditions  of  living  at  some  spots  in  the  desert  suitable  in 
other  respects  for  laboratory  purposes  are  so  severe  as  to  offer  an 
obstacle  to  the  best  work.  A  period  of  such  extreme  heat  as  occurs  in 
summer  at  some  points  of  very  low  elevation,  as  for  example  along  the 
lower  Colorado  river  or  in  the  vicinity  of  Guaymas,  Sonora,  or  the 
difiiculty  of  getting  pure  water  and  good  food,  has  been  an  effective 
argument  against  some  otherwise  good  locations. 

Viewed  from  the  standpoint  of  these  primary  requirements  Tucson 
has  a  climate  of  a  thoroughly  desert  character,  and  a  flora,  including 
mountains  and  plain,  rich  in  species  and  genera.  In  addition  to  its 
situation  in  the  heart  of  the  desert  of  Arizona,  it  is  centrally  located, 
both  as  to  position  and  transportation,  with  reference  to  the  deserts  of 
Texas,  Chihuahua,  New  Mexico,  California,  and  Sonora.  The  city 
has  a  population  of  about  10,000.  It  is  situated  on  a  transcontinen- 
tal railroad,  the  Southern  Pacific,  less  than  four  days'  railway  travel 


lA  DESERT    BOTANICAL    LABORATORY 

from  New  York,  about  one  and  a  quarter  days  from  San  Francisco, 
and  seventeen  hours  from  Los  Angeles.  The  Laboratory  will  be  con- 
nected with  the  city  by  telephone,  and  thence  it  will  be  in  communica- 
tion by  telegraph  and  cable  with  as  much  of  the  world  as  the  sender  of 
a  message  may  require.  The  business  of  the  city  and  the  conduct  of 
its  municipal  affairs  are  largely  in  the  hands  of  progressive  Americans- 
The  members  of  the  Board,  while  outfitting  at  Tucson  for  a  short  trip 
to  the  Santa  Catalina  mountains,  found  a  provision  store  that  would 
have  done  credit  to  a  metropolis.  The  elevation  of  Tucson  is  2,390 
feet,  while  the  highest  of  the  mountains  that  surround  the  plain  in 
which  the  city  lies,  the  Santa  Catalina  range,  reaches  about  6,000  feet 
higher.  The  University  of  Arizona,  with  its  School  of  Mines,  and 
the  Arizona  Agricultural  Experiment  Station  are  located  at  Tucson. 
A  hospital  maintained  by  a  sisterhood  and  known  as  St.  Mary's  Hos- 
pital is  another  of  the  city's  institutions. 

Not  the  least  of  the  advantages  of  Tucson  as  a  center  for  the  activi- 
ties of  the  Laboratory  is  the  broadminded  comprehension  of  the  im- 
portance of  the  purposes  of  the  institution  evinced  by  the  citizens, 
accompanied  by  an  earnest  desire  to  cooperate  in  its  establishment. 
This  appreciation  was  expressed  in  the  practical  form  of  subsidies  of 
land  for  the  site  of  the  building  and  to  serve  as  a  preserve  for  desert 
vegetation,  the  installation  and  construction  of  a  water  system,  tele- 
phone, light  and  power  connections,  and  of  a  road  to  the  site  of  the 
Laboratory,  about  two  miles  from  Tucson  (Plates  XI  to  XIII).  The 
monetary  value  of  these  concessions  is  by  no  means  small,  and  is  much 
enhanced  by  the  generous  spirit  in  which  they  were  tendered.  Presi- 
dent Manning  of  the  Chamber  of  Commerce  and  the  gentlemen  asso- 
ciated with  him  in  a  special  committee  to  aid  in  the  establishment  of 
the  Laboratory  were  quick  to  realize  the  needs  of  the  institution  and 
eager  to  meet  these  needs  with  the  resources  at  their  disposal.  The 
members  of  the  Advisory  Board  gratefully  acknowledge  the  generous 
treatment  accorded  the  Laboratory  by  the  city  of  Tucson  through  its 
Chamber  of  Commerce,  a  body  which  has  placed  under  lasting  obliga- 
tions all  botanists  interested  in  the  purposes  of  the  Laboratory. 

President  Adams  of  the  University  of  Arizona,  and  Professor  R.  H. 
Forbes  of  the  Agricultural  Experiment  Station  also  rendered  impor- 
tant service  in  perfecting  arrangements  and  in  offering  cooperation 
from  their  institutions  which  will  do  much  to  increase  the  efficiency 
of  the  Laboratory. 

History.  —  Historically  Tucson  is  an  interesting  old  town.  It  was 
acquired  from  Mexico  as  a  part  of  the  Gadsden  Purchase  in  1853,  and 


Carn.  Inst.  Wash.  Puis'n  6 


Z   5 


J     '' 


Carn.  Inst.  Wash.  Puu'n  6 


Pi.  AT  I    XII 


Carn.  Inst.  Wash.  Pi  i-.' 


Pl.ATI.  XIII 


HISTORY    OF    TUCSON  I5 

at  that  time  had  of  course  a  population  ahnost  exckisively  Mexican  and 
Papago.  The  beginning  of  its  present  period  of  social  and  architectural 
development  dates  from  the  advent  of  the  Southern  Pacific  Railroad 
in  1880.  As  late  as  1850  Tucson  was  still  walled  for  protection  against 
the  Apache  Indians.  Originally  it  was  an  Indian  village,  at  which 
the  Mexican  mission  church  of  San  Xavier  del  Bac,  nine  miles  south 
of  Tucson,  is  believed  to  have  been  built  about  1690.  Of  the  still 
earlier  history  of  Tucson,  as  a  Papago  Indian  village,  the  following 
extract  from  a  letter  written  by  Mr.  W  J  McGee,  the  ethnologist,  gives 
some  interesting  facts  : 

"The  eastern  base  of  the  mountain  lying  west  of  Tucson,  Arizona,  is  the  site 
of  an  aboriginal  settlement  or  village  of  the  Papago  Indians.  Water  was  taken 
from  the  Santa  Cruz  sand  wash ;  the  bottom  lands  were  in  part  devoted  to  the 
tribal  crop,  beans,  as  well  as  to  corn,  squashes,  etc. ;  most  of  the  habitations, 
chiefly  grass  houses,  were  on  the  low  mesa  west  of  the  sand  wash,  which  is  still 
sprinkled  with  potsherds,  and  where  traces  of  the  early  mission  remain  ;  while 
the  mountain  itself  is  a  trinchera,  t.  e.,  a  fortified  place  of  refuge  from  Apache 
invasions.  The  Papago  name  for  the  settlement  was  the  same  as  their  name  for 
the  mountain,  /.  c,  Tuuk-soon  (all  vowels  having  the  continental  sound)  or 
Black  Base.  The  appropriateness  of  this  name  is  obvious  when  the  mountain  is 
viewed  from  the  south-southeast  in  either  morning  or  afternoon  light,  when  the 
darker  volcanic  rock  forming  the  base  of  the  mountain  shows  clearly  against  the 
gray  mass  above.  The  same  name  is  applied  also  by  the  Indians  to  a  modern 
settlement  some  seventy  five  miles  west-southwest  of  this  site,  /.  e.,  to  the  hill 
and  Indian  village  commonly  called  Little  Tucson.  There  are  no  means  now  of 
determining  with  any  degree  of  certainty  the  aboriginal  population  of  the  site  on 
which  you  are  about  to  locate,  though  it  is  practically  certain,  first,  that  the  in- 
habitants for  some  centuries  before  Columbus  were  the  ancestors  of  the  modern 
Papago ;  second,  that  the  settlement  was  a  part  of  a  series  extending  up  Santa 
Cruz  valley  to  its  head  and  beyond  ;  third,  that  the  prehistoric  Papago,  like  their 
modern  descendants,  were  partly  migratory,  moving  southward  in  autumn  to 
hunt  in  the  sierras  during  the  winter,  and  returning  in  spring  to  replant  their 
crops  ;  and,  fourth,  that  the  settlement  was  permanent,  save  for  the  migrational 
abandonments,  for  centuries  before  the  arrival  of  the  Spanish  explorers  and  mis- 
sionaries. Neither  is  it  possible  to  give  account  of  the  earliest  visitations  of 
Caucasians  ;  Cabeza  de  Vaca  may  possibly  have  approached  the  region  about 
^535>  while  Marcos  de  Niza  in  1539  and  Coronado  in  1540  and  1542  passed  within 
rumor-distance  of  it  during  their  journeyings  up  and  down  the  Rio  San  Pedro ; 
'A  Missionary  of  Arizona,' the  late  Archbishop  Salpointe,  in  writing  his  history 
of  the  old  Church  of  San  Xavier  del  Bac,  inferred  that  this  mission  was  estab- 
lished between  1690  and  1692,  while  in  1699  Padre  Kino  knew  of  the  Papago  vil- 
lage below  the  mission  as  San  Agustin  ;  certainly  this  village  was  a  visita,  or 
visiting  charge,  of  San  Xavier  mission  in  1763,  and  there  was  a  Spanish  settle- 
ment hard  by  in  1776  when  the  presidio,  or  capital,  was  removed  thither  from 
Tubac,  this  Spanish  settlement  being  called  San  Agustin  de  Tuquison  while  the 
aboriginal  village  was  known  as  San  Agustin  del  Pueblito  de  Tuquison ;  and  cer- 
tainly Archbishop  Salpointe,  as  well  as  the  late  Dr.  Coues,  the  editor,  and  Mr. 


1 6  DESERT    BOTANICAL    LABORATORY 

Hodge,  the  annotator,  of  the  Garces  Diary,  etc,  repudiated  the  occasional  claims 
that  a  Spanish  settlement  was  founded  there  in  the  sixteenth  century.  The 
Indian  name  was  variously  rendered,  Teuson,  Tueson,  Tubson,  Tuczon,  Tulqu- 
son,  Tuson  being  among  the  more  reasonable  variants,  while  Tucson  has  pre- 
vailed since  the  Gadsden  Purchase.  The  aboriginal  Papago  name  has,  how- 
ever, remained  in  constant  use  among  the  tribesmen,  who  retain  definite  tradi- 
tions of  the  ancient  settlement,  which  was  still  occupied  by  them  until  within  a 
generation.  It  is  merely  a  curious  coincidence  that  the  origin  of  the  name  may 
be  traced  to  the  Pima  term  styuk-son,  meaning  'dark  '  or  '  brown  spring';  for 
not  only  has  the  Papago  occupancy  and  usage  been  continuous  since  prehistoric 
times,  but  there  is  no '  spring  '  of  any  color  there,  still  less  at  the  desert  settle- 
ment of  Little  Tucson.  The  Papago  village  on  your  site  was  apparently  the 
northeasternmost  permanent  settlement  of  the  tribe;  and  in  1775  Padre  Garces 
found  it  the  last  Christianized  pueblo  in  this  direction,  though  some  leagues 
down  the  valley  he  saw  the  site  of  a  Papago  rancheria  depopulated  a  few  years 
previously  by  Apache  hostilities. 

"It  is  of  interest  to  note  that  the  prehistoric  Papago  was  a  farmer,  and  derives 
his  designation  from  this  fact.  The  characteristic  crop  plant  was  the  native 
bean,  called  pah',  or,  in  the  plural,  papah' ;  and  the  same  term  was  applied  to 
the  tribe  by  neighboring  peoples.  The  Spaniards  slightly  corrupted  the  appel- 
lation, pronouncing  it  Papah'o  (the  final  vowel  feeble  and  obscure),  and  spelling 
it,  with  some  emphasis  of  the  aspirate,  Papago ;  the  Americans  retained  this  or- 
thography, but  pretty  effectually  concealed  the  original  form  of  the  tribal  name 
by  adopting  the  pronunciation  indicated  by  their  own  orthoepy.  The  tribes- 
men themselves  long  ago  accepted  the  name  by  which  they  were  known  among 
other  tribes,  adding  the  descriptive  term  a' a/am — literally,  Beansmen,«'.  <?.,  Bean- 
people.  A  few  of  the  earliest  Spanish  visitors  ascertained  the  meaning  of  the 
tribal  designation,  and  translated  it  Frijoleros ;  but  in  general  its  signification 
was  lost,  and  the  name  was  erroneously  connected  with  the  Spanish  ^a/«  (pope, 
hence  catholic),  the  English  baptized  (referring  to  the  supposedly  acquired 
through  really  aboriginal  custom),  etc.  I  am  not  aware  that  the  name  was 
interpreted  in  English  before  my  first  visit  to  the  tribe  in  1874.  About  Tucson 
and  on  the  reservation  at  San  Xavier  the  Indians  follovk^  the  American  pronun- 
ciation of  their  name ;  toward  the  Mexican  frontier  and  in  Sonora  they  retain  the 
Spanish  (Mexican)  pronunciation  or  their  own  closely  similar  form. 

"You  will  be  interested  in  noting  also  that  the  local  tribesmen  were  among 
the  earliest  and  most  successful  agricultural  experimentalists  of  the  western 
hemisphere.  They  are  desert  folk  par  excellence,  and  entered  into  the  distinc- 
tive solidarity'  of  desert  life  to  a  unique  degree ;  they  scoured  the  Sonoran  plains 
for  chance  water  holes  as  well  as  more  permanent  waters,  carrying  religiously 
hoarded  seeds  ;  they  chased  rain  storms  seen  from  commanding  peaks  for  scores 
if  not  hundreds  of  miles  ;  and  wherever  they  found  standing  or  running  water, 
or  even  damp  soil,  they  planted  their  seeds,  guarded  and  cultivated  the  growing 
plants  with  infinite  patience,  and  after  carefully  harvesting  the  crop,  planted  some 
of  the  finest  seeds  as  oblations,  and  preserved  others  against  the  ensuing  season, 
so  that  the  crop  plants  were  both  distributed  and  improved  from  year  to  year. 
I  have  already  had  occasion  to  point  out  that  agriculture  is  a  necessary  product 
of  desert  life,  since  it  is  only  in  regions  of  extreme  aridity  that  plants  and  animals 
are  forced  into  a  common   solidarity  at  last  controlled  and  guided  by  the  supe- 


Carn.  Inst.  Wash.  Pi  hn  C) 


Plate  XIV 


Carn.  Inst.  Wash.  Plb'n  6 


Pl.ATK   XV 


TORRES  17 

rior  mentality  of  mankind  ;  this  I  described  in  '  The  Beginning  of  Agriculture  ' 
{American  AnfkroJ>ologcst,Yo\.  VIII,  pp.  350-375);  and  the  lesson  I  learned 
from  the  Papago  experimentalists  themselves  as  their  ancestors  learned  it  from 
Nature  long  ago.  They  were  prominent  among  the  aboriginal  makers  of  corn, 
as  well  as  the  bean  and  other  native  crop  plants." 

NOGALES. 

The  region  immediatel}'  about  Nogales,  on  the  border  between  Ari- 
zona and  Sonora,  lies  at  an  elevation  of  about  4,000  feet,  just  below 
the  oak  belt.  The  characteristic  vegetation  of  the  hills  is  of  yucca-like 
plants,  including  species  of  Tucca^  Nolina^  Dasylirion^  and  Agave. 
Shrubs  of  the  ordinary  desert  character  are  few  and  form  no  part  of  the 
vegetative  landscape.  Scattered  oak  trees  of  small  dimensions  appear 
here  and  there  among  the  yuccas  (Plate  XIV). 

TORRES. 

The  plain  in  which  lies  the  railroad  station  Torres  is  at  an  elevation 
of  about  Soo  feet  above  the  sea.  Its  most  characteristic  vegetation  is 
a  growth  of  small  leguminous  trees,  notably  palo  fierro  (  Olneya  tesota) 
and  palo  verde  (Parkinsonia)^  two  species  of  Cercus  of  large  dimen- 
sions {Cereus  tJmrberi  and  C.  sckotiti)  (Plate  XV),  and  two  cylin- 
drical stemmed  species  of  Opuntia.  The  palo  fierro,  meaning  iron- 
wood,  produces  a  very  hard  wood,  which  with  the  lighter  but 
still  hard  mesquite  {Prosopis)  and  the  zygophyllaceous  guaiacan, 
or  lignum  vitae  ( Guaiacum  coulteri) ,  constitutes  the  greater  part 
of  the  fuel  used  on  the  railroad  locomotives.  Palo  fierro  is  con- 
sidered by  the  railroad  oflicials  a  better  fuel,  by  about  25  per  cent, 
than  mesquite,  and  guaiacan  about  10  per  cent  better  than  palo  fierro. 
A  metric  cord  (that  is,  a  pile  3  meters  long  by  i  meter  high  and  0.75 
meter  In  length  of  stick)  of  mixed  palo  fierro  and  guaiacan  was  con- 
sidered by  an  engineer  of  experience  as  the  equivalent,  for  fuel,  of  a  ton 
and  a  half  of  the  ordinary  soft  coal  available  in  the  Southwest.  The  palo 
verde,  of  which  the  region  contains  two  species  and  perhaps  more,  is 
an  especially  abundant  tree.  It  is  in  use  everywhere  for  household 
fuel,  and  one  of  the  species  {Parktnsonia  tnicrophylla)  is  commonly 
employed  as  green  forage  for  horses  in  winter,  the  branches  being  cut 
and  thrown  into  the  corrals,  where  the  horses  eat  the  twigs  to  the 
diameter  of  nearly  half  an  inch.  It  is  probable  that  at  this  season  the 
twigs  contain  a  large  amount  of  stored  food.  Cercus  schottii  as  well 
as  another  smaller  species  of  the  same  genus  are  known  as  sina. 
Cereus  thurberi  is  called  pitahaya.  One  of  the  common  species  of 
Opuntia.,  known  as  siviri,  forms  a  small  tree  8  to  15  feet  high,  with 
cylindrical  joints  about  half  an  inch  in  diameter.      It  possesses  a  sour 


1 8  DESERT    BOTANICAL    LABORATORY 

fruit  which  during  the  season  of  drouth  is  an  important  source  of 
refreshment  to  wild  animals  and  even  to  man.  The  other  common 
cylindrical  stemmed  Opuntia^  called  cholla,  has  several  times  thicker 
joints  and  grows  only  2  or  3  feet  high  but  forms  large  patches  which 
are  a  conspicuous  feature  of  the  vegetation.  Other  woody  plants 
showing  adaptations  to  desert  conditions  are  sangre  de  drago  *  {Jatro- 
pka)  a  shrub  with  whip  like,  at  this  season  wholly  leafless  brown 
stems,  from  which  the  Papago  Indians  make  some  of  their  baskets ; 
vinorama,  a  tree  acacia  (^A.  farnesiana)  with  yellow  scented  flowers; 
papachi,  a  small  rubiaceous  tree  {Rand/a  thurberi)  with  fruit  resem- 
bling in  appearance  a  small  green  orange ;  bebelama,  an  unidentiHed 
tree  with  a  trunk  sometimes  18  inches  in  diameter,  its  wood  so  hard 
and  tough  that  it  is  commonly  used  for  wagon  fellies ;  and  desota,  a 
tree  mimosa  with  pink  flowers  having  the  delicious  odor  of  the  black 
locust  flower  {Robtnia  pseudacacid).  This  desert  produces  also 
several  malpighiaceous  and  other  woody  vines  which  associate  them- 
selves with  clumps  of  the  trees  and  shrubs.  Among  these  vines  are 
the  saramatraka,  a  tuberous  rooted  cereus  with  branching  stems  0.2 
to  0.3  inch  in  diameter,  which  reach  a  length  of  4  feet  or  more, 
growing  through  and  reclining  upon  the  bushes ;  and  the  guarequi 
{Ibervillea  sonorae)^  a  cucurbitaceous  tendril  bearing  plant  whose 
inordinately  thickened  root  and  stem  base  sits  white  and  half  exposed 
upon  the  ground  beneath  some  trellising  shrub  (Plate  XVI). 

Westward  from  Torres  the  vegetation  of  the  desert  continues  with  lit- 
tle change  until  the  line  of  hills  is  approached  beyond  which  the  coun- 
try drops  down  to  a  plain  still  lower  and  nearer  the  waters  of  the  Gulf. 
Here  are  the  tree  ocotillo  {^Fouquieria  ?nacdougalii)  (Plate  XVII), 
brasil  {Haematoxylon) ^  torote  prieto  {Bursera)^  the  tree  morning 
glory  {Ipomoea  arborescens)^  and  the  beautiful  palo  lisso  {Acacia 
willardiana) .  This  last  is  a  small  tree  with  the  whitest  of  bark 
peeling  off  in  tissue  paper  films,  a  slender  trunk  with  graceful  spread- 
ing branches,  and  curious  compound  leaves  made  up  mostly  of  flat 
green  rachis  with  an  extremely  small  leaflet  area  toward  the  summit. 
The  morning  glory  is  a  tree  20  to  30  feet  high,  with  smooth  chalky 
gray  trunk  and  branches,  leafless  at  this  season  throughout,  its  large 
white  flowers  opening  one  by  one  on  the  ends  of  the  naked  branches. 
From  its  white  bark  the  tree  is  sometimes  known  as  palo  bianco,  and 
from  the  gum  or  resin  which  exudes  from  incisions  made  in  it  for  the 
purpose  and  which  is  used  as  incense  in  religious  ceremonies  it  is 
called  also  palo  santo.     Two  trees  pass  under  the  name  torote  bianco, 

*  Locally  corrupted  to  sangrengrado. 


Carn.  Inst.  Wash.  Puh'x  6 


Plate  XVI 


^  p 

5  ."" 


OS     D. 

=  x: 


Carn.  Inst.  >Vasii.  Pl  h'n  6 


I'l    \T1      WIJ 


Carn.  Inst.  Wash.  Pub'n  6 


Plate  XVIII 


Papago  Indian  drinking  from  a  cactus  {Echiiiocarfiis  emoryi)  Avest  of  Torres,    Mexico. 


Carx.  Inst.  Wash.  Plh'x    6 


Plate  XIX 


Carn.  Inst.  Wash.  Pub'n  6 


Platk  XX 


one  a  Bur  sera  with  papery  buff  colored  exfoliating  bark,  the  other  a 
tree  of  very  similar  appearance  but  leafless  in  the  winter  season  and 
suggestive  of  Jatropha. 

It  was  among  these  desert  hills  west  of  Torres  that  we  had  an 
opportunity  to  see  a  Papago  Indian  extract  from  a  bisnaga  (^Echino- 
cactus  emoryi)^  or  barrel  cactus,  water  with  which  to  quench  his 
thirst.  He  cut  the  top  from  a  plant  about  five  feet  high  and  with  a 
blunt  stake  of  palo  verde  pounded  to  a  pulp  the  upper  six  or  eight 
inches  of  white  flesh  in  the  standing  trunk.  From  this,  handful  by 
handful,  he  squeezed  the  water  into  the  bowl  he  had  made  in  the  top 
of  the  trunk,  throwing  the  discarded  pulp  on  the  ground.  By  this 
process  he  secured  two  or  three  quarts  of  clear  water,  slightly  salty  and 
slightly  bitter  to  the  taste  but  of  far  better  quality  than  some  of  the 
water  a  desert  traveler  is  occasionally  compelled  to  use.  The  Papago 
dipping  this  water  up  in  his  hands  drank  it  with  evident  pleasure,  and 
said  that  his  people  were  accustomed  not  only  to  secure  their  drinking 
water  in  this  way  in  times  of  extreme  drouth  but  that  they  used  it  also 
to  mix  their  meal  preparatory  to  cooking  it  into  bread  (Plate  XVIII). 

About  eight  miles  west  of  Torres  Yaki  settlements  begin  (Plates 
XIX  and  XX).  One  abandoned  house  had  a  ridgepole  made  of  a 
palm  trunk.  This  was  notched  in  the  manner  followed  by  the  aborigines 
in  pre-Columbian  times  in  making  a  ladder,  and  it  is  evident  that  it  had 
been  put  to  such  a  use  before  it  was  employed  as  a  ridgepole.  This 
palm  trunk,  it  is  believed,  must  have  been  brought  from  the  mountains 
westward  toward  the  Gulf  of  California,  and  very  likely  it  indicates  the 
occurrence  there  of  groves  of  Neowashingtonia.  This  together  with 
the  presence  of  Guaiacum  and  Haematoxylon  shows  why  this  part  of 
the  Sonoran  desert  is  treated  by  some  American  students  as  belonging 
to  the  tropics,  although  the  desert  character  of  the  region  is  not  at  all 
suggestive  of  the  vegetation  we  are  inclined  to  regard  as  representing  a 
tropical  environment. 

GUAYMAS. 

The  flora  in  the  harbor  of  Guaymas  is  a  desert  flora  similar  to  that 
at  Torres  but  apparently  subjected  to  severer  conditions  of  aridity. 
The  creosote  bush  (^Covillea  tridentata)^  the  plant  most  widely  dis- 
tributed in  the  more  severely  dry  deserts  of  the  southwestern  United 
States,  appears  here  again  after  a  long  intermission  across  the  plains  of 
northern  and  middle  Sonora.  Many  of  the  trees  and  shrubs  are  of  the 
same  species  as  those  in  the  vicinity  of  Torres,  but  of  smaller  growth. 
The  hecho  (  Cereus  pecten-abortg-inum') ,  whose  bur-like  fruits  are  often 
used  for  hair  brushes  by  the  Indians,  had  appeared  along  the  railroad 


30  DESERT  BOTANICAL  LABORATORY 

near  the  station  of  Escalante  south  of  Torres,  but  at  Guaymas  it  was 
replaced  by  a  species  of  similar  habit,  with  different  fruit,  Cereus 
pringlel.  A  remarkable  mixture  of  plants  occurred  along  the  beach 
in  the  salt  waters  of  the  harbor  where  small  mangroves  {Avicennia  and 
Rhizophora)  which  we  are  accustomed  to  associate  with  the  humid 
tropics,  grew  side  by  side  with  Cerezis  tJmrberi^  Ceretis  pringlei^  and 
other  characteristic  desert  plants  (Plates  XXI  and  XXII). 

THE    COLORADO    DESERT. 

The  Colorado  desert  of  California  offers,  along  the  line  of  the 
Southern  Pacific,  several  types  of  vegetative  areas,  the  result  of  soil 
differences.  West  of  the  Colorado  river  bottom,  in  the  gravel  hills, 
the  creosote  bush  (  Covillea  tridentata)  is  the  principal  woody  species, 
the  tops  of  the  ridges  being  so  exceedingly  arid  as  to  be  devoid  even  of 
that  most  drouth  resistant  plant.  Associated  with  the  creosote  bush 
are  the  ocotillo  {^Fotiquieria  splendens')  and  the  ironwood  (^Olneya 
tesota),  and  occasionally  the  mesquite  {Prosopis)^  a  joint  pine 
{^Ephedra)^  and  a  palo  verde  {Parkinsonia  torreyand).  Within 
sight  of  the  railroad,  to  the  southward,  extends  a  line  of  sand  dunes 
from  the  Colorado  river  northwestward  for  about  fifty  miles,  nearly  to 
Flowing  Well.  These  extensive  dunes  we  were  not  able  to  examine, 
but  from  the  fact  that  they  lie  in  what  is  probably  the  most  arid  of  all 
the  deserts  of  North  America,  it  is  believed  that  their  flora  is  well 
worth  critical  geographical  examination. 

At  the  station  Volcano  the  alkali  flats  begin.  At  first  these  have 
little  white  incrustations  and  are  devoid  of  vegetation  except  for  a  few 
saline  plants  along  the  arroyos,  such  as  the  chenopodiaceous  shrubs 
Allem-olfea  and  Suaeda.  At  the  station  Frink,  i6  miles  east  of 
Salton,  white  incrustations  begin.  Here  in  occasional  areas  the  only 
plant  growth  consists  of  clumps  of  Allenrolfea  growing  upon  hum- 
mocks of  earth  rising  above  the  general  level  of  the  alkali  incrusted  soil. 

At  Salton,  which  lies  on  the  edge  of  the  salt  flat  and  near  which  are 
several  saline  or  alkaline  springs,  is  afforded  an  excellent  opportunity 
for  securing  material  of  alkali  resistant  plants.  On  the  sandy  hum- 
mocks desertward  from  the  alkali  incrusted  soil  were  two  salt  bushes 
{Atriplex  canescens  and  -<4.  polycarpa) ,  a  composite  bush  with  burlike 
fruits  (  Gaertneria  dutnosa)^  a  Parosela^a  Stiaeda^  the  mesquite  (^Pro- 
sopis)^  and  an  occasional  Lychim  and  ironwood  tree  (  Ohteya  tesotd)  . 
The  springs  are  sluggish  and  have  built  up  about  themselves  low 
mounds  of  earth.  The  soil,  except  where  the  water  is  actually  emerg- 
ing, had  an  incrustation  of  salt  and  alkali.     Four  plants  make  up  most 


Carn.  Inst.  Wash.  Pub'n  6 


Pl.ATK    \X1 


"5   %- 


Cakn.  Inst.  Wash.  Prii'N  6 


IM.AIK  XXll 


Carx.  Ixst.  WAsir.  Pi  m'n  6 


Pl-Al  K  XXIII 


Carn.  Inst.  Wash.  Puh".n  (> 


Pl.ATE  XXIV 


Cakn.  Inst.  Wash.  Pub'x  6 


Platk  XXV 


Carn.  Ixst.  Wash.  Pib'n  6 


Plate  XXVI 


THE    COLORADO    DESERT  21 

of  the  vegetation,  salt  grass  {Distlchlis  spicata)^  Allenrolfea  occi- 
dentalism reed  (^Phragmites  pkragmites),  and  a  rush  {^Juncus  coop- 
eri) .  This  last  plant  grows  in  enormous  tufts,  and  is  of  pi-onounced 
effectiveness  as  a  soil  builder.  In  some  of  the  moister  springs,  with  soft 
deep  black  mud,  a  three-angled  spike  xu?>h.  {Scirptis  olneyi)  was  found, 
and  in  others  the  arrows  w^eed  of  the  desert  marshes  (  Tessaria  bore- 
alis)  (Plates  XXIII  and  XXIV). 

The  visitor  to  Salton  should  bring  his  own  supplies  and  camp  outfit 
as  no  accomodations  or  supplies  are  available. 

One  of  the  most  convenient  points  from  which  to  visit  the  native 
palm  groves  of  the  Colorado  desert  is  the  town  of  Indio.  The  San 
Bernardino  mountains,  high  and  timbered  in  their  main  western  por- 
tion, send  out  eastward  for  many  miles  into  the  desert  a  low  timberless 
spur.  Its  parched  rocky  slopes  seem,  at  the  distance  of  a  few  miles, 
to  be  devoid  of  any  vegetation  whatever,  but  upon  closer  inspection 
are  found  to  be  sparsely  dotted  with  bushes,  like  the  plains  portion  of  the 
desert.  The  canyons  of  this  spur  open  out  upon  the  valley  in  broad 
deltas  of  gravel  brought  down  by  occasional  torrents.  Just  within  the 
mouths  of  some  of  the  canyons  occur  groves  of  a  native  fan  leaved  palm 
(^Neowashingtonia  Jilifera) .  The  groves  visited  by  us  were  not  those 
nearest  the  town,  about  five  miles,  but  those  to  which  we  were  guided 
under  the  name  Thousand  Palms  canyon,  about  nine  miles  from  Indio. 

The  ordinary  diameter  of  the  trunk  is  about  two  feet  and  the  trees 
at  full  maturity  are  about  fifty  feet  high.  Most  of  the  old  trunks  are 
blackened,  apparently  by  fire.  The  younger  trees  retain  their  dead 
leaves  for  several  years,  folded  downward  over  the  trunk  and  forming 
a  cylindrical  mass  about  eight  feet  through  and  sometimes  eighteen 
feet  in  height.  As  the  trees  grow  taller  the  lower  of  these  dead  leaves 
fall  to  the  ground,  leaving  a  naked  trunk  with  a  head  of  green  leaves  at 
the  summit  and  a  collar  of  dead  leaves  just  underneath  (Plate  XXV). 

All  the  trees  seem  to  stand  on  the  same  general  level,  not  far  above 
the  base  of  the  range.  A  close  inspection  showed  that  they  grew  in  a 
moist  clay  soil,  incrusted  with  alkali.  Apparently  such  rain  as  falls 
upon  the  mountains  and  sinks  into  the  earth  is  caught  upon  this  clay 
table  and  runs  over  it  to  the  exposed  margin,  where  for  several  miles 
it  forms  a  line  of  miniature  oases  containing  the  palms  and  various 
plants  characteristic  of  alkaline  springs  (Plate  XXVI).  These  include 
mesquite  bushes  {Prosopis)^  salt  grass  {Distic/ilis  spicata)^  a  rush 
{Juncus)^  a  sedge  (  Cyperus^^  and  an  orchid  (^Epipactis  gigantea) . 
Within  the  canyon  and  upon  the  delta  were  found  a  few  desert  shrubs 
not   met  with  earlier,  the  leguminous  Parosela  spinosa  and  another 


22  DESERT    BOTANICAL    LABORATORY 

species  of  the  same  genus,  and  the  composite  green  leaved  Peucephyl- 
lutn  schottii. 

West  of  Indio  the  railroad  passes  through  a  strip  of  mesquite  dunes. 
Most  of  the  sand  here  lies  in  hummocks,  each  the  product  of  a  mes- 
quite tree  {Prosopis)  about  which,  and  finally  through  the  branches 
of  which,  the  sand  has  drifted  until  only  the  ends  of  the  branches 
project  and  the  hummock  presents  the  appearance  of  being  covered 
with  a  growth  of  brambles. 

Between  Rimlon  and  Palm  Springs  is  an  area  in  which  the  vegeta- 
tion is  subjected  to  strong  sand  laden  winds,  a  veritable  sand  blast. 
The  western  faces  of  the  wooden  telegraph  poles  ai^e  deeply  cut  within 
two  feet  of  the  ground  by  the  sharp,  driving  sand,  and  the  railroad 
employees  have  found  it  necessary  to  pile  stones  about  the  bases  of  the 
poles  in  some  spots  to  keep  them  from  being  actually  cut  off.  The 
creosote  bushes  have  been  moulded  into  the  most  fantastic  shapes.  One 
of  them  standing  in  the  lee  of  a  small  boulder  ran  its  branches  freely  to 
the  eastward,  but  the  twigs  that  projected  upward  and  outward  beyond 
the  protection  of  the  boulder  were  killed  by  the  sand  blast,  so  that  the 
plant  presented  the  appearance  of  a  miniature  box  hedge  about  a  foot 
and  a  half  high  and  wide,  and  extending  about  four  feet  from  the  rock. 

Clumps  of  Ephedra  and  plants  of  Tucca  mohavenszs,  the  cylin- 
drical stemmed  Opuntia  bigelovii  and  O.  echinocarpa^  and  the  flat 
stemmed  spineless  O.  basilaris  vary  the  desert  vegetation  until,  in  the 
vicinity  of  the  station  Cabezon,  the  creosote  bush  ceases  and  the  white 
sage  {Ramona  polystachya)  and  various  other  plants  from  the  coast- 
ward  side  of  the  San  Bernardino-San  Jacinto  mountain  barrier  come 
out  a  little  way  through  San  Gorgonio  pass  to  meet  the  plants  of  the 
desert. 

THE    MOHAVE    DESERT. 

Ascending  from  the  San  Bernardino  valley  northward  through  the 
long  climb  of  Cajon  pass,  the  railroad  at  last  emerges  from  the  dense 
growth  of  chaparral  and  comes  out  upon  the  elevated  plain  of  the 
Mohave  desert.  About  four  miles  north  of  the  summit  begin  to  occur 
small  groves  of  the  strange  tree  for  which  the  western  part  of  the 
Mohave  desert  is  most  widely  known,  the  tree  yucca  (  Tucca  arbores- 
cens).  Within  a  few  miles  the  desert  becomes  almost  a  forest  of  yucca 
and  juniper  {Juniperus  calif ornica')^  the  former  reaching  a  height, 
ordinarily,  of  12  to  15  feet,  though  occasionally  exceeding  25  feet  and 
attaining  a  diameter  of  nearly  two  feet.  At  the  station  Hesperia  the 
juniper  ends  and  the  creosote  bush  (  Covillea  tridentata)  begins.  As 
still  lower  elevations  are  reached,  the  creosote  bush  becomes,  except 


Cakn    Inst.  Wash.  Piis'n  6 


Platk  XX VII 


<  ^ 


Carn.  Inst.  Wash.  Pih'n  6 


Pl.ATK  XXVIII 


<  -2 

°  i 


PLANT    LIFE    IN    DESERTS  23 

in  the  washes,  the  prevaiHng  bush,  and  continues  throughout  the  long 
waste  of  desert  to  the  Colorado  river.  A  fuller  description  of  the 
vegetation  of  the  Mohave  desert  and  the  areas  to  the  north  is  given  in 
Coville's  Botany  of  the  Death  Valley  Expedition,  cited  in  the  bibliog- 
raphy. 

THE  GRAND  CANYON  OF  THE  COLORADO. 

A  visit  was  made  to  the  Grand  Canyon  of  the  Colorado  with  the 
expectation  that  its  lower  elevations  would  afford  lodgment  for  many 
desert  plants,  and  that  a  descent  from  the  timbered  rim,  at  6,866  feet, 
to  the  river  at  2,436  feet,  would  permit  the  traveler  to  see  in  a  brief 
trip  a  wide  range  of  desert  vegetation.  Although  the  descent  is  full 
of  botanical  interest,  and  does  carry  one  down  through  several  dif- 
ferent belts  of  vegetation,  the  comparatively  limited  number  of 
woody  desert  plants  rendered  the  journey  somewhat  disappointing  from 
the  standpoint  of  the  main  object  of  our  trip.  For  the  first  2,600  feet 
of  the  descent  the  trees  continue,  but  from  that  point  to  the  river  the 
slopes  are  treeless  and  the  vegetation  of  a  desert  character  (Plate 
XXVII) .  One  of  the  most  striking  features  is  extensive  fields  of  a 
rosaceous  shrub,  Coleogyne  rafnosissima,  which  extends  in  an  almost 
pure  growth  over  the  canyon  terraces  at  an  elevation  of  about  3,600 
feet  in  a  soil  seemingly  well  supplied  with  lime  (Plate  XXVIII) .  There 
is  a  notable  absence  of  many  shrubs  which  would  be  present  in  the 
open  desert  at  the  elevations  afforded  by  the  lower  parts  of  the  canyon 
and  which  have  a  seemingly  good  route  for  extension  up  the  canyon 
from  the  Mohave  desert.  The  absence  of  these  plants  is  presumably 
connected  with  the  narrowness  of  the  canyon,  which  besides  pr6\luc- 
ing  abnormal  air  currents  and  temperature  conditions  is  responsible 
for  a  rainfall  greater  than  would  occur  at  the  same  elevations  in  the 
open  desert.  A  cloud  sheet  precipitating  rain  on  the  7,000-foot  plateau 
through  which  the  canyon  passes  would  presumably  continue  to  pre- 
cipitate as  it  drifted  across  the  canyon,  whereas  if  it  should  drift  off  the 
plateau  over  a  desert  of  low  elevation  its  precipitation  would  be  greatly 
lessened  or  would  cease  altogether. 

Plant  Life  in  North  American  Deserts. 
The  term  desert  may  be  applied  to  areas  of  the  earth's  surface 
which  support  a  sparse  vegetation  of  a  more  or  less  specialized  char- 
acter owing  to  inadequate  rainfall,  or  to  the  unsuitable  composition  or 
lack  of  soil.  Of  these  conditions,  scanty  water  supply  may  be  re- 
garded as  of  the  greatest  importance,  and  it  is  to  this  factor  that  most 
deserts  owe  their  existence.      Desert  conditions  arise  in  any  region  in 


24 


DESERT  BOTANICAL  LABORATORY 


which  the  rainfall  is  markedly  less  than  the  amount  of  water  that  evap- 
orates from  the  surface  of  this  liquid  in  the  open  air.  As  the 
amount  of  evaporation  naturally  increases  from  the  polar  regions 
toward  the  tropics  and  is  affected  by  winds  and  elevation  it  follows 
that  no  arbitrary  amount  of  rainfall  may  be  designated  as  an  invari- 
able cause  or  accompaniment  of  arid  or  desert  conditions.  Thus  in  cer- 
tain portions  of  the  tropics  a  rainfall  of  less  than  70  inches  results  in 
aridity,  while  some  of  the  most  fertile  agricultural  districts  in  the  north 
and  south  temperate  zones  receive  scarcely  one  third  this  amount. 

Regions  in  which  precipitation  is  less  than  evaporation  are  charac- 
terized by  a  lack  of  running  streams,  or  of  a  permanent  run-off,  al- 
though in  some  instances  these  districts  may  be  traversed  by  large 
rivers  which  have  their  sources  in  distant  mountain  ranges  as  in  the 
case  of  the  Nile  in  Africa  and  of  the  Colorado  river  in  America.  The 
rainfall  in  a  desert  may  be  so  heavy  at  certain  seasons  as  to  produce 
torrents  of  great  volume,  which  rushing  downward  over  the  slopes 
and  mountain  sides,  wear  distinct  streamways  extending  out  into  the 
plains  below  in  some  instances  for  miles  ;  but  the  flow  soon  ceases  after 
the  rains  have  passed  and  the  stream  beds  become  dusty  channels  until 
the  next  rainy  season.  Striking  examples  of  such  streamways  are  to  be 
seen  in  the  great  Sonoran  desert  in  northwestern  Mexico.  It  is  evident 
that  districts  in  which  the  average  rainfall  is  not  much  greater  than  the 
evaporation  are  in  a  very  critical  condition,  since  in  seasons  of  mini- 
mum precipitation  the  amount  of  water  received  may  be  less  than  that 
lost,  and  drought  may  result,  often  with  direful  effects  on  agricultural 
operations  and  economic  conditions  in  general. 

The  seasonal  distribution  of  the  rainfall  is  a  matter  of  importance  in 
regions  where  evaporation  is  nearly  as  great  as  precipitation.  If  the 
rainfall  occurs  within  a  brief  period  the  remainder  of  the  year  must  be 
extremely  dry  and  the  region  will  show  distinct  desert  conditions  with 
a  tendency  on  the  part  of  the  native  plants  to  develop  marked  storage 
capacity  for  water.  The  distribution  of  the  scanty  rainfall  throughout 
the  year  in  any  region  will  favor  the  development  of  slowly  growing 
xerophytic  forms.     These  factors  are  further  considered  on  page  28. 

Arid  deserts  occur  in  all  of  the  great  land  divisions  and  reach  an 
enormous  extent  in  Africa,  Asia,  and  Australia.  The  most  pronounced 
desert  conditions  of  South  America  are  found  on  the  western  slopes  and 
benches  of  the  Andes,  one  locality,  that  of  Copiapo,  having  an  average 
precipitation  of  0.4  inch  per  year,  and,  so  far  as  known,  is  the  driest 
spot  on  the  earth's  surface.  The  deserts  of  North  America  are  confined 
to  the  Cordilleran  region  and  occupy  plateaus  and  plains  east  and  west 
of  the  main  ranges  to  an  extent  of  more  than  a  million  square  miles. 


Library 
N.  C,  State   College 


METEOROLOGICAL    TABLES 


25 


METEOROLOGY. 

The  principal  features  in  the  distribution  and  total  amount  of  rain- 
fall in  several  localities  which  may  be  included  within  the  arid  regions 
are  given  below.  The  data  concerning  the  maximum  and  minimum 
temperatures  and  rate  of  evaporation  afford  a  means  of  estimating  the 
actual  usefulness  or  availability  of  water  supply  for  the  native  vegeta- 
tion. Thus,  for  example,  evaporation  is  so  great  and  humidity  of  the 
air  so  small,  in  the  southernmost  stations  given,  that  the  effectiveness 
of  the  rainfall  in  meeting  the  needs  of  plants  is  diminished  fifty  or  even 
sixty  per  cent.  Of  the  localities  named  below,  El  Paso,  Fort  Win- 
gate,  Chihuahua,  and  San  Luis  Potosi  may  be  included  in  the  Chihua- 
huan  desert,  and  the  other  places  within  the  Nevada-Sonoran  desert. 


METEOROLOGICAL    TABLES. 

The  following  tables  give  the  mean  rainfall  and  the  absolute  maxi- 
mum and  minimum  temperatures  for  16  stations,  13  in  the  United 
States  and  3  in  Mexico.  All  data  for  the  United  States  stations  are 
from  records  in  the  U.  S.  Weather  Bureau.  Data  for  two  Mexi- 
can stations,  San  Luis  Potosi  and  Chihuahua,  are  taken  from  the 
Monthly  Bulletin  of  the  Central  Meteorological  Bureau  of  Mexico  for 
1901.  The  rainfall  record  for  Torres,  vSonora,  Mexico,  was  cour- 
teously furnished  by  Mr.  T.  Oldendorff,  agent  of  the  Sonora  Railway 
at  that  point.  The  figures  for  this  station  were  copied  from  the  report 
made  daily  to  the  manager  of  the  railway. 


San  Luis  Potosi, 

Fort  Wingate, 

Mexico. 

New  Mexico. 

Max. 

Min. 

Mean 
Rain- 

Max. 

Min. 

Mean 
Rain- 

Max. 

Min. 

Mean 
Rain- 

Max. 

Min. 

Mean 
Rain- 

Temp 

Temp. 

fall. 

Temp. 

Temp. 

faU. 

Temp. 

Temp. 

fall. 

Temp. 

Temp. 

fall. 

No.  of 

Years'  Ob- 

23 

23 

18 

I 

I 

I 

I 

J 

J 

5 

5 

39 

servations. 

0 

Q 

Inches. 

Q 

0 

Inches. 

0 

Inches. 

0 

^ 

Inches. 

Jan. 

77 

5 

0.53 

73 

3« 

0.57 

64 

28 

0.00 

68 

—  10 

1.06 

Feb. 

82 

5 

.42 

79 

3B 

.02 

6q 

33 

•17 

69 

—  3 

1.49 

March 

89 

21 

.40 

79 

42 

•97 

72 

37 

.02 

78 

5 

•95 

^P"' 

98 

29 

.15 

90 

46 

.00 

80 

39 

•05 

82 

19 

•79 

May 

105 

40 

•49 

91 

50 

.46 

82 

56 

.46 

92 

II 

•57 

,  une 

1 1.3 

49 

•39 

9' 

5« 

.08 

86 

62 

.5« 

100 

29 

•57 

.  ^'j 

112 

5b 

2.08 

91 

47 

•94 

4^50 

99 

:.9 

2.29 

August 

no 

52 

1.80 

90 

43 

1.64 

86 

68 

.84 

96 

42 

2.15 

Sept. 

104 

42 

I. II 

82 

56 

•94 

84 

54     i    1.95 

92 

32 

1.26 

Oct. 

94 

28 

.92 

79 

50 

•  15 

84 

55 

2.29 

84 

15 

1.08 

Nov. 

«5 

II 

.50 

71 

40 

1.44 

81 

31 

.00 

81 

« 

•79 

Dec. 

76 

—  5 

•54 

37 

3^2o 

... 

.00 
10.86 

69 
102* 

0 
-16* 

i.oo 

Year. 

113 

-5 

9-33 

91 

37 

10.41 

14.00 

*  15  years'  observations 


26 


DESERT  BOTANICAL  LABORATORY 


Hawthorne, 

Nev. 

Winnemucca 

Nev. 

St.  George,  Utah. 

Fort  Duchesne 

,  Utah. 

Max. 

Min. 

Mean 

Max. 

Mi.. 

Mean 
Rain- 

Max. 

Min. 

Mean 

Max. 

Min. 

Mean 
Rain- 

Temp. 

Temp. 

fall. 

Temp. 

Temp. 

fall. 

Temp. 

Temp. 

fall. 

Temp. 

Temp. 

fall. 

No.  of 

Years'  Ob- 

5 

S 

14 

23 

23 

22 

5 

S 

22 

5 

5 

IS 

servations. 

62 

o 

Inches. 

Inches. 

„ 

P 

Inches. 

0 

Inches. 

Jan. 

-  6 

0.59 

57 

-28 

1.09 

70 

—   I 

0.98 

52 

—34 

0.38 

Feb. 

68 

6 

.40 

69 

—22 

0.88 

79 

I 

.92 

60 

—21 

•47 

March 

75 

14 

.35 

82 

—  3 

0.92 

86 

12 

•53 

75 

0 

•65 

April 

8i 

19 

.20 

83 

12 

0.85 

98 

18 

85 

12 

•65 

May 

85 

31 

.45 

9^ 

17 

1.03 

97 

20 

•36 

91 

25 

.66 

fune 

lOO 

40 

.29 

98 

29 

•65 

114 

36 

.06 

lOI 

33 

.18 

My 

lOI 

26 

.27 

104 

.17 

115 

41 

•44 

104 

34 

•50 

August 

ICO 

46 

•45 

102 

26 

.16 

no 

43 

•65 

lOI 

34 

•57 

Sept. 

95 

30 

•23 

94 

16 

•35 

103 

31 

•42 

94 

17 

•99 

Oct. 

8o 

25 

.31 

87 

10 

•56 

93 

20 

.39 

84 

13 

.61 

Nov. 

78 

19 

•39 

73 

-9 

.67 

81 

13 

.40 

70 

I 

.25 

Dec. 

68 

0 

•57 

65 

-20 

.98 

71 

.96 

52 

—19 

.58 

Year. 

lOI 

-  6 

450 

104 

-28 

8.31 

"5 

—  I 

6.46 

104 

—34 

649 

Fort  Yuma,  Ariz. 

Phoenix,  Ariz. 

Tucson,  Ariz. 

Mohave,  Cal. 

No  of 
Years'  Ob- 
servations 

26 

26 

20 

'' 

17 

22 

6 

6 

15 

5 

5 

26 

Jan. 

Feb. 

March 

April 

May 

_  une 

_  uly 

August 

Sept. 

Oct. 

Nov. 

Dec. 

81 

91 
ICO 

107 

112 

118 
115 
113 
108 

11 

2°2 
25 

11 

44 
52 
61 
60 
50 
41 

11 

Inches. 
0.42 

-.11 

.07 

.04 

T 

.14 

•35 

•  15 

.28 

.11 

8°7 
92 
97 
105 
113 
119 
116 
116 
114 
105 
97 
95 

0 
12 

19 

24 

It 

33 
46 

49 
39 
34 
24 
18 

Inches. 
0.80 

.58 
•30 
•13 
.10 
1.03 
.88 
.64 
.37 

80 
83 
92 
95 
102 
112 
108 
109 
107 
98 

§3 

i°7 
17 
22 
28 

11 

59 
57 
49 
29 
21 
10 

Inches. 

0.79 

.90 

•77 

.27 

•  14 

.26 

2.40 

2.60 

1.16 

.64 

.81 

1. 00 

0 

78 
83 
100 
102 
107 
115 
112 
104 

li 

70 

16 

1 

48 
64 
57 
45 
40 
27 
15 

Inches. 
0.95 
•92 
•75 
•17 
•03 
•05 
.08 
.04 
.07 
.25 
.40 
1.26 

Year. 

118 

22 

2.84* 

119 

12 

693 

112 

10 

11.74 

115 

15 

4.97 

'26  years'  observations. 


Prineville,  Oreg. 

Lost  River,  Idaho. 

Laramie,  Wyo. 

Torres,  Mex. 

No.  of 
Years'  Ob- 
servations. 

6 

6 

6 

5 

5 

5 

1 

'       1       ' 

1 

13 

Rainfall. 
190T 

Rainfall. 
1902 

Jan. 

Feb. 

March 

April 

May 

June 

July 

August 

Sept. 

Oct. 

Nov. 

Dec. 

76 
73 
83 
92 
96 
98 
119 
III 

t 

82 
76 

0 

-  9 
—17 

5 
12 
21 
24 
29 
30 
20 
20 

9 

—  5 

Inches. 
0.64 
1.09 
.81 
.64 
.80 
•77 

.64 
.81 

:S 
•97 

0 

45 
49 
62 
76 
90 

i 
48 

—26 
—41 
—  I 
14 
15 
23 
30 
25 
21 
14 

—  8 
—23 

Inches. 

1.12 
.26 
•91 
•35 

1.27 
.68 
.61 
.64 
■44 
•63 
.92 
.8. 

52 

It 
It 

91 
92 
91 
85 

l"" 
63 
52 

-23 

—40 

—14 

—10 

18 

28 

33 

32 

17 

7 

— 12 

—27 

Inches. 
0.23 
•35 
•91 
1.19 
1.41 
1. 12 
1.30 
1.09 

Inches. 
3-99 

Ms 

.21 

Inches. 
0.00 

.00 

.00 

.00 

.00 

.00 
7.26 
3.01 
4.69 

.04 

•77 
1.02 

Year. 

119 

—17 

9.01 

99 

—41     1   8.65  1     92     |— 40 

9.81 

16.79 

METEOROLOGICAL    DISCUSSION 


The  ratio  of  rainfall  to  evaporation  cannot  be  exactly  determined  as 
data  for  evaporation  are  meager  or  wholly  lacking.  It  has  been  deemed 
worth  while  nevertheless  to  get  an  approximate  notion  of  this  ratio  by 
estimating  the  evaporation  and  dividing  by  the  normal  rainfall.  In 
the  following  table  this  has  been  done  and  the  results  appear  in  the 
last  column  headed  Ratio.  This  table  also  shows  the  maximum  and 
minimum  annual  precipitation  at  each  station  during  the  observation 
period  shown  in  column  2. 


Annual  Precipitation 

Annual 
Evapora- 

No. of 
Years. 

Max. 

Min., 

Mean. 

tion 
(Estim.). 

Inches. 

Inches. 

Inches. 

Inches. 

24 

18.30 

2.22 

923 

80 

8.7 

I 

10.41 

... 

I 
39 

6.37 

10.86 
14.00 

"So 

25.00 

5-7 

26 

5.86 

0.60 

2.84 

100 

35.2 

18 

12.83 

3-77 

7.06 

90 

12.7 

25 

18.37 

5-26 

11.74* 

90 

7-7 

26 

21.38 

2.20 

4-97 

95 

19. 1 

14 

8.35 

1.89 

4.50 

80 

17-5 

22 

II. 91 

4.89 

8.31 

80 

9.6 

13 

9.81 

3-55 

6.46t 

1         90 

'3-9 

15 

11-43 

4-36 

6.49 

1         75 

II. 6 

6 

11.64 

7-49 

9.01 

i        70 

7-8 

7 

11.86 

6.22 

8.47 

!     70 

8-3 

13 

31-42 

5-56 

9.81 

70 

7-1 

I 

16.79 

100 

6.0 

El  Paso 

San  Luis  Potosi 

Chihuahua 

Fort  Wingate... 

Fort  Yuma 

Phoenix 

Tucson 

Mohave 

Hawthorne 

Winnemucca.... 

St.  George 

Fort  Duchesne. 

Prineville 

Lost  River 

Laramie 

Torres 


*From  15  years  observations.  tFrom  22  years  observations. 
Discussion. —  The  foregoing  meteorological  data  are  given  concern- 
ing localities  which  very  clearly  lie  within  the  true  desert  regions  of 
North  America.  It  would  be  impossible  to  outline  the  included  areas 
upon  a  map  except  by  means  of  data  obtained  by  an  accurate  and  ex- 
tended hydrographic  and  biological  survey.  The  rate  of  evaporation 
for  the  several  localities  mentioned  is  roughly  estimated  from  data 
taken  from  the  Report  on  the  Climate  of  Arizona  by  Greely  and  Glass- 
ford  in  1891.  It  is  probable  that  actual  measurements  might  show 
a  variation  of  ten  per  cent  by  way  of  error  in  these  estimates,  but  the 
amount  given  may  be  regarded  as  fairly  approximate  for  the  regions  in 
which  the  several  stations  are  located.  It  is  to  be  seen  that  the  evapo- 
ration at  Tucson,  Arizona,  and  at  Laramie,  Wyoming,  is  about  seven 
times  as  great  as  the  normal  precipitation,  while  the  evaporation  at 
Yuma,  Arizona,  is  more  than  thirty-five  times  as  great  as  the  average  or 
normal  amount  of  precipitation.  The  evaporation  at  the  last  named 
locality  amounted  to  one  hundred  and  sixty  times  as  much  as  the  pre- 
cipitation in  the  year  1899. 


28 


DESERT    BOTANICAL    LABORATORY 


The  seasonal  distribution  of  the  rainfall  in  a  region  in  which  the 
normal  precipitation  bears  a  low  ratio  to  evaporation  may  not  only 
exert  a  marked  influence  on  the  character  of  the  vegetation,  but  may 
also  operate  to  produce  desert  conditions  and  make  possible  the  sup- 


FiG.  I.     Location  of  and  annual  precipitation  at  certain   stations  in  the  arid 
region  of  Western  America.    Chiefly  from  records  of  the  U.  S.  Weather  Bureau. 

port  of  xerophytic  vegetation  only,  in  districts  with  a  large  amount  of 
rainfall.  Thus  if  the  greater  part  of  the  precipitation  should  occur 
during  a  season  of  low  temperature,  or  in  the  quiescent  period  of  the 


METEOROLOGICAL    DISCUSSION  29 

native  species  the  resulting  dryness  of  the  growing  season  would  result 
in  desert  conditions.  Such  effects  are  most  marked  in  regions  in  which 
the  surface  layers  of  the  substratum  consist  of  loose  material  not  capa- 
ble of  retaining  water  in  sufficient  quantity  for  moisture  loving  spe- 
cies. A  striking  example  of  this  feature  is  offered  by  the  area  around 
Crater  lake,  Oregon,  as  described  by  Mr.  Coville.  The  surface 
layers  in  this  locality  consist  of  powdered  pumice  apparently  almost 
devoid  of  humus,  from  which  water  drains  with  extreme  rapidity. 
Snowfall  to  a  depth  of  about  lo  feet  occurs  in  winter,  but  after  this 
melts  the  soil  becomes  extremely  dry  and  the  plants  capable  of  endur- 
ing the  resulting  drouth  show  marked  protective  adaptations,  the  vege- 
tation consisting  chiefly  of  such  species  as  Phlox  douglasii^  Spraguea 
umbellata^  and  Arenaria  pumicola.  ^ 

The  above  factors  must  be  taken  into  account  in  the  interpretation 
of  alpine  districts  in  many  parts  of  the  world.  The  precipitation  on 
mountain  summits  is  very  gi^eat  but  in  some  instances  it  is  in  the  form 
of  snow  which  melts  and  drains  away  very  rapidly  leaving  the  humus- 
free  soil  extremely  dry,  while  the  air  shows  rapid  alternations  from 
high  to  extremely  low  relative  humidity.  An  example  of  this  char- 
acter is  offered  by  the  summit  of  Agassiz  peak  in  the  San  Francisco 
mountains  of  northern  Arizona,  an  illustration  of  which  is  shown  in 
Plate  XXIX,  facing  page  43.  A  further  description  of  the  meteorolog- 
ical conditions  on  this  mountain  will  be  found  on  pages  38  to  45. 


The  chief  factor  in  the  production  of  deserts  is  a  lack  of  water  as  a 
nutrient  substance  for  vegetation.  Deserts  may  be  produced  as  a  re- 
sult of  other  defective  nutritive  and  mechanical  conditions  as  well. 
Such  conditions  are  to  be  found  in  areas  in  which  the  soil  contains 
harmful  substances  in  injurious  concentration  in  the  soil,  of  which  the 
alkali  lands  are  familiar  examples.  Sterile  areas  due  to  lack  of  nutri- 
tive material  and  water,  and  to  the  unsuitable  mechanical  conditions  of 
the  soil  are  offered  by  stretches  of  sand  dunes  and  plains  in  many  parts 
of  the  world.  In  sand  dunes  the  substratum  is  in  constant  motion  of 
greater  or  less  rapidity,  lacks  a  suitable  water  supply,  and  may  be  devoid 
of  other  nutritive  material.  Even  if  the  dune  areas  are  supplied  with 
water  in  proper  quantities,  yet  the  peculiar  character  and  niovemcnts 
of  the  substratum  result  in  some  striking  forms  of  vegetation. 

1  Coville,  F.  V.  The  home  of  Botrychium  fumicola.  Bull  .Torr.  Bot.  Club, 
28:  109.  1901.  The  August  vegetation  of  Mount  Mazama,  Oregon.  Mazaina, 
I  :   170.  1896. 


30 


DESEKT    BOTANICAL    LABORATORY 


A  combination  of  the  above  mechanical  and  physical  conditions  of 
the  soil  and  of  the  presence  of  harmful  substances  is  offered  by  the 
White  Sands  district  in  the  Tularosa  desert  in  New  Mexico,  of  which 
a  more  detailed  description  is  given  on  pages  5  to  10.  The  sand  dunes  in 
this  distinct  consist  chiefly  of  gypsum,  the  principal  remaining  con- 
stituents being  silicates  and  calcium  chloride  in  the  proportions  of 
3  per  cent  and  i  per  cent  respectively.  The  gypsum  is  slowly  soluble 
in  cold  water  and  retains  the  greater  amount  of  .the  water  which 
falls  upon  it.  Consequently  the  dunes  are  really  moist  hillocks  of  a 
granular  structure,  the  surface  layers  of  which  are  dried  out  by  the  heat 
of  the  sun  to  a  depth  of  a  few  inches.  The  dried  layer  is  constantly 
drifted  by  the  wind,  and  the  exposed  layers  are  dried  in  turn  so  that 
the  progressive  action  of  sand  dunes  is  manifested.  The  underlying 
layers  at  some  depth  often  become  solidified  and  stratified,  but  are 
easily  broken  up  when  exposed  to  the  action  of  the  sun  and  wind. 
The  moisture  included  is  sufficient  for  a  number  of  species  of  plants, 
but  the  mineral  substances  in  solution  makes  it  possible  for  only  those 
forms  which  are  adapted  to  an  alkaline  substratum  to  gain  a  foothold. 
The  White  Sands  absorb  the  entire  precipitation  and  give  rise  to  no 
distinct  streams,  but  occasional  small  pools  or  tanks  of  water  highly 
charged  with  calcium  salts  are  to  be  found  in  areas  among  the  dunes. 
In  western  Austi'alia  extensive  areas  of  gypsum  desert  are  to  be  found 
which,  it  is  reported,  form  a  distinct  harder  surface  crust  instead  of  a 
granular  layer  as  in  the  instance  described  above  but  no  exact  anal- 
yses of  the  substratum  are  at  hand. 

A  number  of  districts  in  America  show  enclosed  pockets  or  basins 
forming  the  extreme  lower  depressions  of  ancient  lake  and  river  beds, 
in  which  the  soil  is  highly  charged  with  salts,  the  most  of  which  is 
sodium  chloride.  Examples  of  this  character  are  offered  by  the  region 
around  Great  Salt  lake,  Utah,  and  by  the  Salton  district  in  the  Colo- 
rado desert  of  southern  California.  The  characteristic  vegetation  in 
both  instances  is  composed  of  species  showing  halophytic  adaptations, 
resembling  those  found  near  the  seashore. 

Limited  areas  in  various  regions  show  soils  impregnated  with  sodium 
sulphate,  sodium  carbonate,  potassium  sulphate,  sodium  phosphate, 
sodium  nitrate,  calcium  sulphate,  calcium  chloride,  magnesium  chloride, 
and  magnesium  sulphate.  In  agricultural  operations  two  types  of 
such  soils  are  recognized,  namely  :  white  alkali  and  black  alkali. 

The  nature  of  the  mixture  in  the  soil  constituting  white  alkali  is 
illustrated  by  the  following  analyses  : 


SOIL    ANALYSES 


31 


SURFACE    CRUST    OF    SOIL    FROM    KERN    ISLAND,    BAKERSFIELD,    CALIFORNIA. 


ANALYSIS    BY    HILGARD.' 

Potassium  sulphate, 

Sodium  sulphate, 

Sodium  chloride. 

Sodium  carbonate, 

Magnesium  sulphate. 

Magnesium  carbonate. 

Calcium  phosphate. 

Calcium  sulphate, 

Ferric  and  aluminum  oxides, 

Silica, 

Organic  matter  and  water  of  crystallization, 


Per  Cent. 

•52 

82.96 

.48 

.40 

•50 

•13 

.20 

.10 

•30 

1-34 

4.07 


ALKALI    FROM   THE   VALLEY    OF    THE   RIO    GRANDE     IN    NEW     MEXICO  :    ANALYSIS 

BY    GOSS    AND    GRIFFIN '^    MADE   FROM    THREE    SAMPLES    FROM 

DIFFERENT    LOCALITIES. 


No.  3- 


Insoluble  matter 

Portion  soluble  in  water 

Composition  of  soluble  portion. 

Potassium  oxide 

Sodium  oxide 

Calcium  oxide 

Magnesium  oxide 

Aluminum 

Sulphates 

Chlorides    

Carbonates 

Water  of  crystallization  and  organic  matter 


Per  cent. 
75-59 


4-71 

3772 

5-57 

.98 

3-24 

10.16 

4796 

Trace 

.44 


74.24 
25-76 

3-57 

28.97 

6.60 

1-55 

0.00 

47.72 

4-58 

Trace 

8.04 


34-40 
65.60 

.21 

31-38 

7.92 

1.05 

0.00 

52.67 

1.20 

Trace 

584 


The  composition  of  the  impregnating  salts  producing  the  black  alkali 
is  shown  by  the  following  analysis  of  alkali  salts  from  soil  near  Fresno, 
California.  ^ 

Per  cent. 

Potassium  chloride,  1.30 

Sodium  sulphate,  18.23 

Sodium  chloride,  35-93 

Sodium  carbonate,  18.72 

Sodium  bicarbonate,  25.72 

Phosphoric  acid,  .lo 

1  Hilgard,  E.  W.  Report  of  Work  of  the  Agricultural  Experiment  Stations 
for  the  year  1900,  p.  97. 

^Goss  and  Griffin.  Bull.  No.  22,  New  Mexico  Agric.  Exp.  Station,  p.  26, 
March,  1897. 

"Means  T.  H.  and  Holmes,  J.  G.  Soil  survey  around  Fresno,  Calif.  Field 
Operations  of  the  Division  of  Soils,  U.  S.  Dept.  of  Agriculture.  Second  Report, 
P-  373.  1900. 


DESERT    BOTANICAL    LABORATORY 


HISTORICAL. 

The  current  conceptions  of  deserts  are  neither  adequate  nor  correct 
if  the  descriptions  in  the  best  dictionaries  and  cyclopedias  are  to  be 


Fig.  2.  Western  America  showing  conceptions  of  American  deserts  current  in 
1835.  Copied  from  T.  G.  Bradford's  Comprehensive  Atlas,  published  at  Boston 
in  1835. 

taken  as  an  index.     A  work  of   wide  circulation  and  use  defines  a 
desert  as  "  A  region  that  is  wholly  or  approximately  without  vegetation. 


HISTORICAL 


33 


Such  regions  are  rainless,  usually  sandy,  and  commonly  not  habitable." 
Another  characterizes  a  desert  as  "A  region  of  considerable  extent 
which  is  almost  if  not  quite  destitute  of  vegetation,  and  hence  unin- 
habited, chiefly  on  account  of  an  insufficient  supply  of  rain  :  as.  the 
desert  of  Sahara ;  the  Great  American  Desert.  The  presence  of  large 
quantities  of  movable  sand  on  the  surface  adds  to  the  desert  character 
of  a  region.  The  w^ord  is  chiefly  and  almost  exclusively  used  with 
reference  to  certain  regions  in  Arabia,  and  northern  Africa  and  others 
lying  in  central  Asia.  The  only  region  in  North  America  to  which 
the  word  is  applied  is  the  Great  American  Desert,  a  tract  of  country 
south  and  west  of  the  Great  Salt  Lake,  once  occupied  by  the  waters  of 
that  lake  when  they  extended  over  a  much  larger  area  than  they  now 
occupy.  The  name  Great  American  Desert  was  originally  given  to 
the  unexplored  region  lying  beyond  the  Mississippi  without  any  special 
designation  of  its  limits"  (Fig.  2). 

The  insufficiency  of  the  above  descriptions  obviously  rests  upon  faulty 
observations,  and  upon  the  failure  to  recognize  the  fact  that  the  habita- 
bility  of  a  region  is  no  criterion  of  its  arid  character.  The  development 
of  modern  methods  of  transportation  has  made  possible  the  maintenance 
of  dwellings  and  towns  with  a  considerable  population  at  one  or  even 
two  hundred  miles  from  the  nearest  supply  of  water.  Even  such  facil- 
ities are  not  necessary  to  the  sustenance  of  a  population  in  deserts  of  the 
most  extreme  type  as  illustrated  by  the  Sahara  which  has  a  popula- 
tion of  two  and  a  half  million  people.  So  far  as  the  vegetation  is 
concerned  the  actual  number  of  individuals  is  much  less  than  on  a  sim- 
ilar area  in  a  moist  climate ;  this  in  fact  is  one  of  the  chief  characteris- 
tics of  a  desert,  but  it  would  not  be  safe  to  estimate  the  total  number 
of  species  much  below  the  average  number.  Lastly,  be  it  remembered 
that  local  topography  has  but  little  influence  on  the  desert  character  of 
a  region.  Sandy  flats,  plains,  valleys,  and  rocky  hills  reaching  to  such 
altitudes  as  to  become  mountains  are  included  in  some  desert  tracts. 
It  follows  as  a  natural  consequence  of  the  sparse  vegetation  as  one 
factor,  that  the  surface  layers  of  the  substratum,  being  usually  dry  in 
arid  regions,  are  readily  shifted  and  worn  by  winds. 

The  designation  of  the  vast  region  between  the  Missouri  river  and 
the  Rocky  mountains  as  the  Great  American  desert  rested  upon  a  lack 
of  definite  knowledge  by  the  earlier  geographers,  which  was  shown  by 
text  books  as  recently  as  1843.  Later,  when  the  more  exact  results  of 
the  earlier  explorations  and  surveys  became  known,  the  more  important 
arid  regions  were  fairly  well  delimited  and  the  desert  areas  in  the  Bad 
Lands,  the  Staked  Plains  of  Texas,  the  Chihuahua  desert,  the  Great 


34  DESERT    BOTANICAL    LABORATORY 

Basin  and  the  Colorado  desert  were  shown  approximately  within  the 
districts  which  may  appropriately  be  designated  as  desert  at  the  present 
time.  This  conception  of  the  matter  is  shown  in  F'ig.  J,  being  a  map 
from  a  text  book  on  physical  geography  published  in  1859. 

Further  exploration  and  utilization  of  desert  areas  in  agricultural  and 
mining  operations  led  to  the  abandonment  of  the  term  desert  as  applied 
to  all  the  regions  shown  in  -P'lg.  3  except  those  about  the  lower  Colo- 
rado river  and  near  Great  Salt  lake.  A  study  of  the  physiographic,  flo- 
ristic,  and  meteorological  features  of  western  North  America  has  re- 
sulted in  delimiting  two  great  desert  areas  by  the  geographer,  botanist, 
and  meteorologist.  The  outlines  of  these  might  be  roughly  traced  by 
lines  connecting  the  stations  shown  in  I^t'g'.  i.  These  regions  may  be 
designated  as  the  Sonora-Nevada  desert  and  the  Chihuahua  desert. 

The  Sonora-Nevada  desert  embraces  portions  of  Utah,  Idaho, 
Washington,  Oregon,  Nevada,  California,  Arizona,  Baja  California, 
Sonora,  and  Sinaloa.  The  northern  portion  of  this  region  is  mainly 
comprised  in  the  Great  Basin  and  embraces  the  beds  of  a  number 
of  ancient  lakes  and  the  surviving  Great  Salt  lake.  Other  special 
physiographic  features  of  interest  in  this  connection  are  the  areas 
which  bear  the  names  of  Snake  River  desert  of  Idaho  ;  The  Sage 
plains  of  Washington ;  the  Lava  Beds  of  Oregon ;  the  Ralston  desert  in 
Nevada ;  Death  Valley,  Mohave  desert,  Colorado  desert,  Salton  desert, 
in  southern  California  and  Arizona ;  the  Painted  desert  in  Arizona 
and  New  Mexico ;  and  the  Sonora  desert  in  Mexico.  The  southern 
portion  of  the  region  consists  of  a  series  of  extended  slopes  and  ter- 
races traversed  by  many  ranges  of  hills  and  mountains  with  peaks 
of  some  altitude.  Along  the  shores  of  the  Gulf  of  California  and  of 
the  Pacific  Ocean  proper,  the  desert  area  includes  the  entire  surface 
to  within  a  few  feet  of  the  water's  edge  and  the  xerophytic  vegeta- 
tion of  the  plains  comes  into  direct  contact  with  the  mangrove  and 
strand  flora. 

The  Chihuahua  desert  occupies  the  central  table  land  of  Mexico  east 
of  the  Sierra  Madre,  extending  as  far  south  as  San  Luis  Potosi  and  in- 
cluding parts  of  the  states  of  Coahuila,  Chihuahua,  and  Texas  and  also 
portions  of  Arizona  and  New  Mexico.  The  Bad  Lands  of  the  Dakotas 
and  Montana  and  the  Red  desert  of  Wyoming,  both  included  in  the 
"Great  American  desert"  (Fig.  2),  might  be  regarded  as  a  north- 
ern arm  of  this  region  for  the  purposes  of  this  paper.  The  arid 
portions  of  this  area  consist,  for  the  most  part,  of  great  valleys  en- 
closed by  parallel  ranges  of  mountains  which  in  some  instances  attain 
such  altitudes  as  to  be  timber  clad  and  even  bear  an  alpine  vegetation. 


HISTORICAL 


35 


One  of  the  striking  features  of  the  Chihuahua  desert  consists  of  the 
great  sand  dunes,  or  "  medanos,"  more  than  a  hundred  feet  high,  in 
some  instances  forming  great  ridges  that  have  almost  the  imposing  ap- 
pearance of  mountain  ranges ;  these  move  across  the  floor  of  the  desert 


Fig.  3.  Western  America  showing  conceptions  of  American  deserts'current  in 


1859.     Copied  from  Warren's  Physical  Geography,  published  in  1S59. 
plains  with   a  sweep  that  obliterates  minor  features  of    topography. 
These  moving  dunes  bear  a  characteristic  vegetation  adapted  to  the 
unusual  physical  conditions  offered  by  the  sand  and  lack  of  water  and 
nutrient  material.     The  gypsum  deposits  forming  the  White  Sands  in 


36  DESERT    BOTANICAL    LABORATORY 

the  Tularosa  desert  north  of  the  Rio  Grande  have  already  been  men- 
tioned. The  Jornada  del  Muerto  (Journey  of  Death)  of  the  ancient 
Spanish  explorers  lies  in  the  western  portion  of  the  Chihuahua  desert 
in  New  Mexico  separated  from  the  Tularosa  desert  by  the  Organ 
mountains.  Further  northward  the  great  stretches  of  malpais^  or  black 
volcanic  rock,  form  a  desert  district  of  the  extreme  type,  while  numer- 
ous areas  are  impregnated  with  alkali,  and  are  either  almost  wholly  free 
from  vegetation  or  support  only  halophytic  species.  The  Bad  Lands 
of  Dakota  owe  their  desert  character  to  the  peculiar  composition  of  the 
soil  which  is  clayey,  poor  in  nutrient  substances,  and  subject  to  great 
erosion  so  that  extensive  areas  are  destitute  of  vegetation  of  any  kind. 

Observations  upon  the  striking  forms  of  xerophytic  vegetation  char- 
acteristic of  arid  regions  have  been  made  by  occasional  explorers  in 
various  parts  of  the  world ;  among  these  are  to  be  noted  the  writings 
of  Philippi  on  the  desert  of  Atacama  on  the  west  coast  of  South 
America,  published  in  i860.  The  accounts  of  the  earlier  surveys  of 
western  America  also  contain  some  interesting  information  concerning 
some  of  the  features  of  the  flora  of  the  desert  regions.  The  first  gen- 
eral studies  of  the  flora  of  arid  regions  were  made  by  Volkens  and 
by  Maury,  whose  results  were  published  in  1887  and  1888. 

Volkens  made  some  examination  of  the  physiographic  and  climatic 
conditions  in  the  deserts  of  Arabia  and  Egypt  and  also  of  the  relation 
to  habitat  of  some  of  the  characteristic  species.  His  treatment  of  the 
functional  performances  of  xerophytic  plants  indigenous  to  this  region 
is  based  upon  anatomical  characters  almost  wholly,  and  no  effort 
appears  to  have  been  made  to  measure  the  actual  work  acccomplished 
by  the  plant  under  any  of  the  conditions  described.  The  detailed 
study  made  of  the  general  structure  and  vegetative  habit  of  a  large 
number  of  species  resulted  in  the  acquisition  of  a  rich  mass  of  anatom- 
ical facts,  upon  which  our  present  knowledge  of  the  properties  of  desert 
plants  chiefly  rests. 

Maury  also  made  an  examination  of  the  general  features  of  the  mi- 
nute anatomy  of  xerophytic  plants  from  the  Sahara  region,  and  sets 
forth  the  principal  adaptations  which  these  species  have  undergone  in 
response  to  their  arid  environment. 

The  work  of  Warming  upon  the  flora  of  the  dry  savannas  at  Lagoa 
Santa  in  Brazil  is  also  to  be  regarded  as  an  important  contribution  to 
the  general  subject  of  desert  vegetation.  A  fairly  complete  bibliogra- 
phy of  the  entire  subject  forms  the  concluding  section  of  this  report. 

In  1 89 1  Mr.  Frederick  V.  Coville  made  a  botanical  investigation  of 
the  Death  Vallev  region  in  southern  California.     The  work  was  de- 


TRANSPIRATION    AND    TEMPERATURES 


37 


signed  to  be  both  systematic  and  comprehensive.  It  embraced  a 
delineation  of  the  principal  vegetative  conditions  to  be  met  with  in 
deserts,  some  investigations  of  the  relations  of  the  chief  environmental 
factors  to  the  characteristic  plants,  and  an  examination  of  the  more 
important  adaptations  of  a  large  number  of  species.  One  of  the  fea- 
tures of  this  contribution  deemed  of  great  importance  was  the  recog- 
nition of  the  major  problems  to  be  encountered  and  an  outline  of  fur- 
ther researches  needed  upon  the  subject.  The  region  included  in  this 
survey  consists,  in  large  part,  of  mesas  in  which  Covillea  and  Gaert- 
neria  are  the  prevailing  plants.  The  surface  layers  of  the  soil  consist 
of  gravel,  sand,  and  boulders.  An  average  of  the  data  obtained  by  the 
ten  Weather  Bureau  stations  nearest  the  region  showed  a  rainfall  of 
about  5  inches  annually,  and  a  precipitation  amounting  to  1.54  inches 
was  observed  in  the  region  itself  from  January  to  June  inclusive  in  1S91 . 
The  extreme  dryness  of  the  atmosphere  is  illustrated  by  the  fact  that  the 
relative  humidity  at  5  P.  M.  taken  daily  during  the  five  months  men- 
tioned was  15.6  per  cent.  On  the  4th  and  5th  of  August  of  the  same 
season  a  minimum  of  5  per  cent  was  recorded.  A  maximum  temper- 
ature of  122°  was  recorded  five  times  during  the  summer  season  of  1S91 
and  a  minimum  of  30°  was  reached  in  January  and  February  of  the 
same  year.  Vegetation  in  this  district  was  seen  to  exhibit  its  great- 
est activity  during  the  period  of  maximum  precipitation  with  medium 
temperatures  from  February  to  May ;  a  quiescent  condition  during  the 
season  of  maximum  temperature  and  dryness  during  June  to  Novem- 
ber :  and  a  condition  of  slow  growth  during  the  low  temperatures  of 
December  and  January. 

Perhaps  the  most  noteworthy  result  of  this  study  of  the  flora  con- 
sisted in  the  discovery  that  the  vegetation  was  composed  almost  wholly  of 
perennial  shrubs  and  annual  herbs,  and  but  few  adaptations  were  found 
for  storage  of  water.  The  tendency  to  form  fleshy  fruits  was  almost 
lacking  and  even  the  fruits  of  Opuritia  were  comparatively  dry  and 
hard.  The  root  systems  of  a  number  of  plants  were  examined  and  the 
mesquite  {Prosopis)  was  found  to  have  roots  more  than  50  feet  long. 
Growth  or  increase  in  length  and  thickness  was  found  to  be  extremely 
slow  in  the  perennials,  though  very  rapid  in  the  annuals  which  carry 
out  their  entire  vegetative  and  reproductive  cycle  during  the  period  of 
maximum  precipitation.  Many  interesting  facts  are  also  cited  as  to  the 
uses  of  hairy  coverings  and  resinous  coating  in  the  prevention  of  dam- 
age by  extreme  evaporation  of  water  and  intense  radiation. 


38  DESERT    BOTANICAL    LABORATORY 

TRANSPIRATION    AND    TEMPERATURES. 

Mr,  D.  T.  MacDougal,  in  1898,  made  a  series  of  experiments  at 
Turkey  Tanks  on  the  western  edge  of  the  malpais  or  lava  desert  near 
the  Little  Colorado  river  east  of  Flagstaff,  Arizona.  In  these  attention 
was  chiefly  given  to  the  amount  of  transpiration  and  to  the  tempera- 
tures of  the  soil,  of  the  air,  and  of  the  bodies  of  succulent  plants,  the 
results  of  which  are  now  given  for  the  first  time. 

Measurements  of  transpiration  were  made  by  means  of  a  potonieter 
of  the  form  described  in  the  Bota7tical  Gazette  (24  :  1 10,  1897).  This 
apparatus  consists  of  a  long  calibrated  tube  of  small  internal  diameter 
supported  in  a  horizontal  position  and  fitted  with  a  Y  extension  at  one 
end.  The  tube  is  filled  with  water  and  the  excised  shoot  of  a  plant 
fitted  to  one  end  of  the  Y  by  means  of  a  tightly  wired  section  of  rub- 
ber tubing.  The  other  end  of  the  Y  is  closed  by  a  stopcock,  which 
may  be  opened  to  admit  water  when  necessary.  The  rate  at  which 
water  is  taken  into  the  shoot  is  noted  by  the  progress  of  an  air  bubble 
in  the  horizontal  portion  of  the  tube.  It  is  to  be  borne  in  mind  that 
the  rate  at  which  water  may  be  absorbed  by  the  basal  portion  of  an 
excised  shoot  in  contact  with  water  may  not,  and  probably  does  not, 
represent  the  exact  rate  at  which  transpiration  actually  takes  place,  but 
it  offers  a  very  valuable  method  of  comparison  of  the  capacities  of 
shoots  of  various  types  to  take  up  and  throw  off  water  under  similar 
conditions. 

Experit7ient  i.  —  Me7itzelia pu7nila  is  a  representative  of  a  class  of 
plants  which,  annually  growing  from  seeds,  produce  flowers  and  seed 
during  the  season  of  greatest  humidity,  and  then  die,  the  species  sur- 
viving through  the  resting  season  in  the  form  of  seeds.  It  is  a  marked 
example  of  the  xerophytic  species  which  have  a  weakl}^  developed 
root  system  consisting  of  a  number  of  thin  branching  fibrous  roots 
which  extend  chiefly  laterally  through  the  upper  layers  of  soil  and  do 
not  penetrate  beyond  a  depth  of  a  few  inches.  The  aerial  shoot  has  a 
roughened  cylindrical  stem  about  16  inches  long  and  a  number  of 
lateral  branches  of  equal  length  giving  the  entire  leafy  shoot  a  globoid 
outline,  a  form  characteristic  of  many  desert  plants.  The  specimen 
used  was  furnished  with  18  branches  and  bore  about  900  irregular 
narrow  roughened  leaves  and  200  yellow  flowers.  The  entire  surface 
of  the  portion  of  the  plant  exposed  to  the  air  might  be  estimated  at 
about  800  square  inches.  The  plant  was  taken  from  the  soil  after  the 
above  facts  had  been  ascertained,  and  the  root  system  was  cut  away 
from  the  base  of  the  stem  before  attachment  to  the  potometer  as  above. 
Several  minutes  were  allowed  to  elapse  before  observations  were  taken 


TRANSPIRATION    AND    TEMPERATURES  39 

to  allow  the  plant  to  recover  from  the  shock  of  handling,  to  which  it 
had  been  subjected. 

At  the  beginning  of  the  experiment  the  apparatus  stood  in  the  shade 
of  a  small  pitiyon  tree  with  a  fitful  movement  of  the  air  at  a  temperature 
of  80°  F.  During  the  first  few  minutes  of  the  observations  in  which 
equalization  of  the  negative  pressure  was  in  progress,  the  time  in  which 
a  unit  (100  miUigrams)  of  water  was  taken  up  was  as  follows  :  40, 
45,  42,  48,  47,  50,  50,  50,  50,  50,  50  seconds,  or  at  the  rate 
of  2  to  2.5  milligrams  per  second.  Half  an  hour  later,  at  10.30 
A.  M.,  after  the  negative  pressure  had  been  equalized  tests  were  made 
in  the  open,  with  the  sky  clouded,  and  the  air  at  a  temperature  of  84" 
F.  The  periods  in  which  100  milligrams  were  absorbed  were  75,  70, 
80,  85,  85,  90,  and  95  seconds,  giving  a  rate  of  1.05  to  1.4  milligrams 
per  second.  With  continued  cloudiness,  and  the  air  at  a  temperature 
of  88°  F.  beginning  at  10.50  A.  M.,  the  periods  were  75,  75,  60,  70, 
70,  75  seconds  or  at  a  rate  of  1.3  to  1.4  milligrams  per  second.  The 
sun  emerging  from  the  clouds  the  readings  of  400  milligrams  in  150 
seconds,  400  milligrams  in  210  seconds,  and  300  milligrams  in  150 
seconds  were  taken,  giving  an  average  rate  of  1.9  to  2.2  milligrams 
per  second.  With  the  return  of  the  clouds  immediately  afterward  the 
readings  were  400  milligrams  in  210  seconds,  500  milligrams  in  330 
seconds,  900  milligrams  in  600  seconds,  or  an  average  rate  of  1.9  milli- 
grams per  second,  decreasing  to  1.5  per  second  as  the  effects  of  the 
cloudiness  were  felt.  The  rate  again  rose  to  1.8  and  1.9  milligrams 
per  second  as  the  sun  emerged  from  the  clouds. 

Experiment  2,  Artemisia  sp.  was  used  in  this  test.  It  is  a  low 
densely  branching  shrub  with  an  extensive  root  system  of  the  deeply 
penetrating  type.  It  stands  nearl}^  inactive  throughout  the  dry  season, 
taking  on  a  quickened  growth  as  demonstrated  by  the  formation  of 
new  shoots  and  reproductive  organs  within  a  month  after  the  beginning 
of  the  July  rains. 

Amain  branch  with  30  branchlets  about  12  inches  long  was  fastened 
to  the  potometer  at  9  A.  M.,  July  16,  with  the  air  temperature  75°  F. 
Readings  of  700  milligrams  in  17  minutes,  400  milligrams  in  10  min- 
utes were  made  with  the  sun  obscured  by  clouds.  In  sunshine  readings 
of  1,100  milligrams  in  25  minutes,  900  in  19  minutes,  500  in  12  minutes, 
and  500  in  16  minutes  were  made  with  an  average  of  .6  to  .7  milli- 
gram per  second.  The  total  area  of  the  surface  of  the  branch  and 
leaves  was  about  960  square  inches. 

As  a  means  of  comparison  similar  tests  were  made  with  the  same 
piece  of  apparatus  on  moisture  loving  plants  in  the  physiological  labo- 
ratory at  the  University  of  Minnesota. 


4©  DESERT    BOTANICAL    LABORATORY 

Experiment  3.  —  A  well  grown  shoot  of  the  tomato  with  a  total 
surface  of  256  square  inches  was  fastened  to  the  potometer  in  a  room 
in  diffuse  light  with  a  humidity  of  25  to  35  per  cent.,  about  the  same  as 
in  the  previous  experiments,  at  a  temperature  of  79°  F.  Readings  of 
1,000  milligrams  in  32  minutes,  and  600  milligrams  in  21.2  minutes 
were  made,  giving  an  average  rate  of  about  .5  milligram  per  second 
and  subsequent  observations  showed  no  important  deviation  from  this 
rate.  It  is  to  be  noted  that  the  conditions  differed  from  those  of  the 
desert  plant  in  the  lower  temperature  and  the  much  lower  intensity  of 
the  light. 

Experiment  4. — Eucalyptus  globulus  was  used,  being  the  shoot  of  a 
young  plant  grown  from  seed  in  the  greenhouse  and  having  a  surface  of 
352  square  inches.  The  test  was  made  at  the  same  time  of  day  (10  to 
II  A.  M.),  and  under  approximately  the  same  conditions  as  experi- 
ment3.  Readings  of  500  milligrams  in  7.5  minutes,  9.5  minutes,  10.5 
minutes,  10  minutes,  and  10  minutes  were  made  with  an  average  rate 
of  .79  to  I.I  I  milligrams  per  second. 

The  data  furnished  by  the  above  tests  afford  a  fair  means  of  com- 
parison of  the  relations  of  moisture  loving  and  desert  plants  to  water 
if  due  allowance  is  made  for  dissimilar  conditions.  It  is  to  be  seen 
that  a  given  area  of  surface  of  Mentzelia  at  similar  temperatures  and 
in  a  light  vastly  more  intense  and  in  a  drier  atmosphere,  transpires 
water  at  a  rate  slightly  less  than  the  tomato  and  at  a  rate  about  a  third 
to  a  half  that  of  Eucalyptus.  The  exposure  of  the  two  last  named 
species  to  similar  temperatures,  insolation,  and  dryness  of  the  air  would 
doubtless  show  that  the  moisture  loving  plants  would  take  up  and  lose 
water  at  a  rate  even  much  greater  than  the  Mentzelia. 

The  shrubby  Artetnisia  was  found  to  use  water  at  a  rate  per  area 
about  one  fourth  that  of  the  tomato  under  the  dissimilar  conditions 
offered.  An  increase  of  the  temperature,  insolation  and  dryness  of  the 
air  affecting  the  tomato  would  doubtless  increase  the  ratio  many  times. 
The  Eucalyptus  would  offer  even  greater  disproportion. 

Still  another  interesting  suggestion  arises  from  these  results.  Ment- 
zelia is  an  annual  that  carries  on  its  growth  only  during  the  season  of 
maximum  humidity,  while  Artemisia  is  an  example  of  the  perennial 
shrubby  plant  which  makes  no  reduction  of  its  surfaces  during  the  dry 
seasons.  The  latter  therefore  must  be  better  protected  against  the 
dangers  of  drought  and  actually  uses  only  about  half  the  amount  of 
water  per  area  of  surface  that  is  needed  by  Mentzelia.,  and  it  sends  its 
roots  to  enormous  depths  to  ensure  a  constant  supply  to  keep  up  a 
steady  but  slow  rate  of  transpiration. 


TRANSPIRATION    AND    TEMPERATURES  41 

No  measurements  were  made  of  the  intensity  of  the  insolation,  but 
a  comparison  of  the  conditions  with  those  prevalent  in  other  localities 
in  which  photometric  work  has  been  carried  out  would  tend  to  the 
conclusion  that  it  is  higher  than  that  of  1.6  units  recorded  in  the  East 
Indian  tropics,  an  effect  due  to  the  low  relative  humidity  of  the  desert 
atmosphere.  The  intensity  of  the  insolation  may  affect  plants  in  three 
ways  of  interest  in  connection  with  the  purpose  of  this  paper.  The 
action  of  the  blue-violet  rays  may  exercise  a  disintegrating  effect  upon 
the  protoplasmic  constituents  of  the  organism.  The  attainment  of  the 
higher  temperatures  as  a  result  of  the  conversion  of  light  rays  into 
heat  may  reach  the  maximum  limit  of  the  activity  of  protoplasm ;  also 
the  critical  point  at  which  chlorophyl  begins  to  undergo  chemical  de- 
terioration, and  the  action  of  the  sunlight  upon  the  soil  would  result  in 
the  attainment  of  temperatures  affecting  the  development  and  absorp- 
tive activities  of  the  root  system.  In  order  to  obtain  data  bearing 
upon  these  points  the  following  observations  were  made  : 

July  16.  The  bulb  of  a  mercurial  thermometer  was  pushed  down 
into  the  soil  around  the  root  tips  of  a  clump  of  bunch  grass  to  a  depth 
of  2  inches,  and  the  glass  stem  of  the  instrument  shaded  from  the 
direct  rays.  The  soil  consisted  of  a  mixture  of  volcanic  sand  and  al- 
luvial deposit.  At  2.20  P.  M.  a  temperature  of  106°  F.  was  recorded. 
A  few  minutes  later  108°  F.  with  the  air  ranging  from  91.4°  to  93.2° 
F.  At  3  P.  M.  the  black  volcanic  sand  around  the  roots  of  Cleoine 
serrulata  Pursh  showed  a  temperature  of  111°  F.  with  the  air  at 
113°  F.  Professor  Toumey  cites  the  fact  that  the  temperature  of  the 
soil  at  the  depth  of  one  inch  near  Tucson  reaches  a  temperature  of  113** 
F.  with  a  mean  average  of  104.9°  F.  for  the  entire  month  of  July. 
Also  that  the  average  for  the  month  of  July  at  a  depth  of  4  feet  was 
82°  F.  with  a  maximum  of  84.5°  F.  and  a  minimum  of  Si°  F.  The 
writers  are  indebted  to  Professor  Toumey  for  the  statement  that  the 
temperature  of  the  soil  near  Tucson  increases  slowly  during  July,  re- 
mains stationary  during  August,  and  begins  to  decrease  in  September. 
These  observations  are  of  great  interest  since  the  insolation  would  be 
practically  identical  with  that  near  Flagstaff,  although  the  altitude  of 
the  latter  place  is  somewhat  greater.  The  soil  in  which  the  observa- 
tions at  Tucson  were  made  consisted  chiefly  of  decomposed  granite 
with  some  mica. 

Mr.  A.  E.  Douglass,  of  the  Lowell  Astronomical  Observatory  at 
Flagstaff,  Arizona,  has  communicated  some  observations  indicating  that 
the  sandy  soil  around  the  roots  of  small  herbaceous  plants  in  the  Grand 
Canyon,  Arizona,  on  September  4,  1898,  exhibited  temperatures  as 
high  as  148°  F. 


42 


DESERT    BOTANICAL    LABORATORY 


The  temperatures  of  a  number  of  plants  were  obtained  by  Mr.  Mac- 
Dougal  by  thrusting  the  bulbs  of  small  mercurial  thermometers  into 
the  fleshy  stems,  and  shading  the  exposed  portion  of  the  instrument 
from  the  sun's  rays.  The  following  data  were  recorded  from  tests  of 
this  character  with  an  Optintia  (probably  O.  engelmannii')  on  July 
17,  1898. 


Temperature  of  Opuntia. 

,  Temperature  of  Air. 

7.20  A.  M. 

79.0° 

F. 

78.5°  F. 

8.10  A.  M. 

93-5 

82.4 

9  A.M. 

93-8 

87.8 

10.30  A.  M. 

97.2 

91.4 

II  A.  M. 

III. 2 

96.8 

11.30  A.  M. 

109.4 

100.4 

12.30  P.  M. 

108.0 

100.4 

The  flattened  fronds  of  the  cactus  were  in  an  upright  position  with 
the  edges  in  the  plane  of  the  meridian,  so  that  the  angle  of  the  incident 
rays  of  sunlight  decreased  with  the  altitude  of  the  sun.  As  a  conse- 
quence of  this  insolation  the  resulting  temperatures  rise  until  about  10 
A.  M.,  and  then  decrease  until  the  sun  once  more  comes  into  a  posi- 
tion where  the  rays  might  strike  the  surface  at  or  near  a  right  angle, 
reaching  a  second  maximum  at  2  P.  M.,  though  Mr.  MacDougal's 
observations  on  this  point  were  somewhat  obscured  by  the  daily  cloud- 
ing at  the  time  of  the  experiments.  In  the  thermometry  of  globular, 
decumbent  or  cylindrical  forms  of  fleshy  plants  such  as  Cereus 
temperatures  of  113°  to  115°  F.  were  often  found  with  the  air  at  a 
temperature  of  93°  to  100°  F.  It  is  to  be  seen  that  plants  in  this 
region  are  subject  to  the  action  of  a  fierce  insolation  and  to  an  atmos- 
phere of  low  relative  humidity.  As  a  result  of  such  insolation  the 
body  of  the  plant  and  the  surface  layers  of  the  soil  are  raised  to  very 
high  temperatures.  The  increase  in  temperature  of  the  shoot  aided  by 
the  direct  action  of  the  light  upon  the  transpiratory  mechanism  would 
tend  to  increase  the  amount  of  water  given  off  by  the  shoot.  At  the 
same  time  however  the  temperature  of  the  soil  undergoes  a  correspond- 
ing increase,  thereby  increasing  the  osmotic  processes  of  absorption  so 
that  the  two  processes,  absorption  and  transpiration,  automatically 
equalize  each  other,  provided  the  maximum  temperature  of  proto- 
plasmic activity  is  not  passed. 

It  is  to  be  noted  that  the  amount  of  evaporation  or  transpiration  of 
water  from  a  leaf  must  be  sufficient  to  keep  the  temperature  of  the 
leaves  and  other  green  organs  below  the  critical  point  of  chlorophyl, 
or  the  temperature  at  which  it  begins  to  suffer  chemical  decomposition 
as  a  result  of  heat.     This  critical  temperature  is  usually  given  as  1 13°  F., 


Carn.  Inst.  Wash.  Plu'-n  6 


Pl.ATK  XXIX 


Alpine  desert  on  summit  of  San  Francisco  mountain,  Arizona,  with  meteorological 
instruments  in  position. 


TRANSPIRATION    AND    TEMPERATURES  43 

while  the  writers  have  observed  numbers  of  bodies  of  plants  in  which 
the  midday  temperature  reached  115°  and  116°  F.  without  injury,  and 
from  their  location  must  have  undergone  similar  conditions  repeatedly. 
This  gives  rise  to  two  suggestions.  The  protoplasm  of  plants  which 
have  become  adapted  to  this  region  must  have  undergone  certain  vari- 
ations in  composition,  as  its  maximum  point  of  activity  is  beyond  that 
of  other  plants,  and  these  forms  must  also  be  furnished  with  specially 
adapted  chloroplasts  by  which  the  chlorophyl  would  be  kept  from  in- 
jury at  temperatures  beyond  the  critical  point  at  which  it  suffers  damage 
in  other  plants.  The  existence  and  growth  of  certain  algit  in  the  waters 
of  hot  springs  lends  favor  to  this  supposition.  It  is  however  probable 
that  the  death  of  plants  which  have  found  foothold  in  such  regions  may 
result  from  the  intense  insolation  quite  as  much  as  from  a  lack  of  a  proper 
supply  of  water. 

In  connection  with  the  above  observations  it  was  deemed  important 
to  make  some  comparative  observations  upon  the  climatic  features 
encountered  by  alpine  plants,  and  Mr.  MacDougal  in  company  with 
Mr.  A.  E.  Douglass  and  his  assistants  made  an  ascent  of  San  Francisco 
mountain  north  of  Flagstaff,  and  about  fifteen  miles  due  west  from 
the  station  at  which  the  observations  on  desert  plants  were  made  but 
at  an  elevation  about  a  mile  higher.  Camp  was  made  and  maintained 
during  the  first  week  in  August,  1898,  at  an  elevation  of  1 1 ,500  feet  and 
in  addition  to  the  astronomical  equipment  a  battery  of  instruments 
including  a  thermograph,  a  hygrograph,  and  mercurial  thermometers 
were  allowed  to  remain  on  the  summit  at  12,500  feet  for  fifteen  days 
(Plate  XXIX) .  The  records  obtained  of  the  temperature  and  relative 
humidity  of  the  air  are  given  in  the  accompanying  diagram  (Fig.  4). 

It  is  to  be  seen  that  the  temperature  of  the  air  does  not  undergo  such 
great  diurnal  variation  as  that  at  lower  altitudes.  A  greater  difference 
is  to  be  found  between  the  temperature  of  the  soil  and  air,  however, 
than  at  lower  elevations.  At  an  elevation  of  3,000  feet  the  mean 
temperature  of  the  soil  in  humid  localities  is  2.7°  F.  greater  than 
that  of  the  air;  at  4,000  feet  it  is  3°  F. ;  at  5,000  feet,  4.3°  F.  ;  at 
6,000  feet  it  is  5.4°  F.  and  at  7,000  feet  it  is  6.5°  F.  In  an  observa- 
tion made  at  4  P.  M.  August  8,  on  the  western  slope  of  the  peak  the 
soil  stood  at  71.6°  F.  and  the  air  at  57.6"  F. ;  and  at  7  A.  M.  the  next 
morning  the  Uiinimum  of  21.2°  F.  was  obtained  for  the  air  and  48.2°  F. 
for  the  soil.  This  increase  in  the  difference  between  the  temperature 
of  the  soil  and  the  air  is  due  to  the  increase  in  intensity  of  the  sun's 
rays  and  the  attenuation  of  the  atmosphere  at  such  altitudes.  It  is  esti- 
mated that  the  intensity  of  the  sun's  rays  at  an  altitude  of  9,000  feet  is 


44 


DESERT    BOTANICAL    LABORATORY 


1 1  per  cent  greater  than  at  the  sea  level  in  a  humid  atmosphere,  and 
that  the  intensity  is  26  per  cent  greater  at  an  altitude  of  15,600  feet,  on 
the  summit  of  Mont  Blanc,  than  at  sea  level.  It  is  to  be  seen  by  refer- 
ence to  the  curve  of  humidity  that  the  amount  of  moisture  in  the  air  in 
the  locality  under  discussion  is  at  times  extremely  small,  which  would 
further  intensify  the  insolation.  It  would  be  entirely  safe  therefore  in 
a  comparison  of  this  summit  with  that  of  Mont  Blanc  to  say  that  the 


Fig.  4.  Meteorological  data  from  San  Francisco  mountain,  Arizona,  Aug.  8 
to  Aug.  19,  1898.  The  upper  curve,  traced  from  the  hygroscopic  record  shows 
variations  in  relative  humidity.  The  lower  curve  shows  the  corresponding  air 
temperature  in  the  shade.  The  instruments  were  in  the  shelter  shown  in  Plate 
XXIX. 


intensity  of  the  sun's  rays  is  at  least  25  per  cent,  greater  than  at  sea 
level  and  about  12  per  cent,  more  than  on  the  plain  below,  which  by  its 
altitude  and  other  conditions  would  in  turn  be  about  1 2  or  13  percent, 
greater  than  at  sea  level. 

The  species  of  plants  inhabiting  this  and  all  alpine  situations  are  al- 
most altogether  perennials,  passing  the  unfavorable  season  in  the  form 
of  a  fleshy  or  woody  rootstock.  The  aerial  shoots  are  generally  pros- 
trate and  lie  close  to  the  ground,  a  device  generally  conceded  to  be 
due  to  the  thermotropism  of  the  plant  whereby  it  receives  all  possible 
advantage  of  the  higher  average  temperature  of  the  soil  than  of  the 
air.      So  far  as  the  structural  features  of  alpine  plants  are  concerned  it 


TRANSPIRATION    AND    TEMPERATURES  45 

is  to  be  seen  that  a  general  similarity  to  that  of  desert  forms  is  exhib- 
ited. The  outer  integument  of  the  plant  is  developed  in  such  manner 
and  furnished  with  devices  for  the  prevention  of  damage  from  the  ef- 
fects of  the  intense  insolation,  and  for  preventing  rapid  radiation. 
Either  cause  would  result  in  an  excessive  transpiration  and  damage  to 
the  chlorophyl  apparatus  and  protoplasmic  mechanism.  No  important 
anatomical  features  of  plants  at  high  altitudes  or  high  latitudes  have 
yet  been  discovered  which  might  unquestionably  be  interpreted  as 
adaptations  to  an  alpine  or  polar  climate. 


46  DESERT    BOTANICAL    LABORATORY 


BIBLIOGRAPHY. 

By  William  Austin  Cannon. 

Note  :  This  list  of  publications  is  arranged  in  four  groups.  In  the  first,  pages 
46  to  52,  are  included  g-eneral treatises ;  in  the  second,  pages  52  to  53,  those  relat- 
ing to  climate;  in  the  third,  pages  53  to  57,  those  relating  to  soil  and  in  the 
fourth,  pages  57  to  58,  those  relating  to  water. 

GROUP    I.    GENERAL. 

Aitchison,  J.  E.  T. 

1889     A  summary  of  the  botanical  features  of  the  country  traversed  by  the 
Afghan  Delimitation  Commission  during  1884-85.     Trans,  and  Proc. 
Bot.  Soc.  Edinb.  17  :  421. 
Altenkirch,  G. 

X894     Studien  iiber  die   Verdunstungsschutzeinrichtungen   in  der  trockenen 
Gerollflora  Sachsens.      Bot.  Jahrb.  18  :  354. 
Areschoug,  F.  W.  C. 

1882     Der  Einfluss  des  Klimas  auf  die  Organisation  der  Pflanzen,  insbesondere 
auf  die  anatomische  Structur  der  Blattorgane.     Bot.  Jahrb.  2  :  511. 
Bary,  E.  v. 

1878    Ueber  den  Vegetationscharakter  von  Air.     Zeitschr.  Gesells.    Erdkunde 
zu  Berlin,  13  :  350. 
Brandis,  D. 

1887     Regen  und  Wald  in  Indien.     Meteorolog.  Zeitschr.  4  :  369. 
Bray,  W.  L. 

1901  The  ecological  relations  of  the  vegetation  of  western  Texas.     Bot.  Gaz. 
32  :  99,  195,  262. 

Bryden,  B.  A. 

1893     Gun  and  camera  in  southern  Africa.     London. 
Bunge,  A.  v. 

1880     Pflanzen-geographische  Betrachtungen  iiber  die  Familie  der  Chenopo- 
diaceen.     Mem.  Acad.  Imp.  Sci.  St.  Petersburg,  VII.  27**. 
Campbell,  M.  R. 

1902  Reconnaissance  of  the  borax  deposits  of  the  Death  Valley  and  Mohave 
Desert.     Bull.  U.  S.  Geol.  Survey,  No.  200. 

Carnegie,  D.  W. 

1898  Spinifex  and  sand.     M.  F.  Mansfield  and  Co.,  New  Vork. 
Cockerell,  T.  D.  A. 

1897     Life  zones  in  New  Mexico.     N.  M.  Ag.  Exp.  Sta.  Bull.  No.  24. 

1899  Vernal  phenomena  in  the  arid  region.     Am.  Nat.  33  :  39. 
Coville,  F.  V. 

1892     Descriptions  of  new  plants  from    southern   California,  Nevada,  Utah, 
and  Arizona.     Proc.  Biolog.  Soc.  Washington,  7:  65. 


BIBLIOGRAPHY 


47 


Coville,  F.  v.— continned. 

1892     Sketch  of  the  flora  of  Death  Valley,  California.     Science,  20  :  342. 

1892  The  Panamint  Indians  of  California.     Am.  Anthropologist,  5  :  351. 

1893  Botany  of  the  Death  Valley  expedition.     Cont.  U.  S.  Nat.  Herb.  4. 
1896     The  sage  plains  of  Oregon.     Nat.  Geog.  Mag.  7  :  395. 

1896  The  August  vegetation  of  Mt.  Mazama,  Oregon.     Mazama,  i :    170. 

1901  The  home  of  Botrychium  pumicola.     Bull.  Torr.  Bot.  Club,  28  :    109. 
Davy,  J.  B. 

1898  Natural  vegetation  of  alkali  lands.  Calif.  Ag.  Exp.  Sta.  Report 
1895-6  :  63. 

1902  The  native  vegetation  and  crops  of  the  Colorado  delta  in  the  Salton 
basin.     Calif.  Ag.  Exp.  Sta.  Bull.,  No.  140  (Supplement). 

Detto,  C. 

1903  Ueber  die  Bedeutung  der  atherischen  Oele  bei  Xerophyten.  Flora,  92  : 
147. 

Eastwood,  A. 

1893     General  notes  of  a  trip  through  southeastern  Utah.     Zoe,  3  :  354. 

1893     List  of  plants  collected  in  southeastern   Utah,  with  notes  and  descrip- 
tions of  new  species.     Zoe,  4  :  113. 
(Editorial.) 

1890  Origin  and  character  of  the  Sahara.     Science,  16:   106. 
Farini,  G.  A. 

1886     Through  the  Kalahari  Desert.     London. 
Feret,  A. 

1897  Les  plantes  des  terrains  sales.     Le  Monde  des  Plantes,  7  :   182,  193. 
Fernow,  B.  E. 

X897     The  forests  and  deserts  of  Arizona.  Proc.  Am.  Forestry  Assoc.  12  :  71. 
Forbes,  R.  H. 

1895  The  mesquite  tree  :  its  products  and  uses.   Arizona  Exp.  Sta.  Bull.  No.  13. 

1896  Canaigre.     Arizona  Exp    Sta.  Bull.  No.  21. 
Fountain,  P. 

1901     The  great  deserts  and  forests  of  North  America.     Longmans,  Green, 
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Gilg,  E. 

1891  Beitrage  zur  vergleichenden  Anatomie  der  xerophilen  Familie  der  Res- 
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Gillmore,  P. 

[1878]     The  great  thirst  land.     London,  Paris  and  New  York. 
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1849  Plantse  Fendlerianse  Novi-Mexicanae  :  an  account  of  a  collection  of 
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Am.  Acad.  4:1. 

1850  Plantse  Lindheimerianie,  Part  2.  An  account  of  a  collection  of  plants 
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1853  Plantse  Wrightianse  Texano-Neo-Mexicana.     Pt.  IL    Washington. 

1854  Plantae  novae  Thurberianae  :  the  characters  of  some  new  genera  and 
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48  DESERT    BOTANICAL    LABORATORY 

Grisebach,  A. 

1872     Die  Vegetation  der  Erde.     Leipzig. 
Hackel,  E. 

1890     Ueber    einige    Eigenthiimlichkeiten    der    Graser    trockener    Klimate. 
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Hall,  H.  M. 

1902     A  botanical  survey  of  San  Jacinto  mountain.      Univ.  Calif.  Pub.  Bot. 
I  :    I. 
Hartz,  N. 

1895  Ostgronlands  Vegetationsforhold.  Meddelelser  om  Gronland,  18  :  105. 
Havard,  V. 

1884  The  mezquit.     Am.  Nat.     May,  18  :  451. 

1885  Report  of  the  botany  of  southern  and  western  Texas.  Proc.  U.  S.  Nat. 
Mus.  8  :  449. 

Heinricher,  E. 

1885  Ueber  einige  im  Laube  dikotyler  Pflanzen  trockenen  Standortes  auftre- 
tende  Einrichtungen,  welche  muthmaasslich  eine  ausreichende  Wasser- 
versorgung  des  Blattmesophylls  bezwecken.     Bot.  Centralb.  23:  25,  56. 

Henslow,  6. 

1894     The  origin  of  plant-structures  by  self-adaptation  to  the  environment, 
exemplified  by  desert  or  xerophilous  plants.     Jour.  Linn.  Soc.  Lond. 
Bot.  30:  218. 
Hough,  W. 

1898  Environmental  interrelations  in  Arizona.  Am.  Anthropologist,  11  :  133. 
Jaffa,  M.  E. 

1894     Australian  salt  bush.     Calif.  Ag.  Exp.  Sta.  Bull.  105  :  10. 

1896  Analysis  of  Australian  salt  bush.  Calif.  Ag.  Exp.  Sta.  Report  1894-95  : 
165. 

James,  £. 

1823     Account  of  an  expedition  from   Pittsburg  to  the  Rocky  Mountains  in 

1819-20,  under  the  command  of  Maj.  S.  H.  Long.     Philadelphia. 
1825     Catalogue  of  plants  collected  during  a  journey  to  and  from  the  Rocky 
Mountains  during  the  summer  of  1820,  etc.     Trans.  Am.  Phil.  Soc.  II. 
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Johnson,  D.  W. 

1902     Notes  on  the  geology  of  the  saline  basins  of  central  New  Mexico.    Ann. 
N.  Y.  Acad.  Sci.  14  :  161.     (Abstract.) 
Jones,  M.  E. 

1900     The  Great  Salt  Lake  desert.     Contr.  to  Western  Bot.  9  :  50. 
Kerner  von  Marilaun,  A. 

1886  Osterreich-Ungarns  Pflanzenweldt.  Die  Osterreich-Ungar.  Monarchic 
in  Wort  und  Bild.  2.     Wien. 

Kjellman,  F.  R. 

1884  Ur  polarvaxternas  lif.  Nordenskiold's  Studier  och  Forskningar.  7  :  461. 
Knoblauch,  E. 

1896  Okologische  Anatomic  der  Holzpflanzen  der  siidafrikanischen  immer- 
griinen  Buschregion.      (Diss.  Univ.  Giessen.)    Tubingen. 


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1894  Die  Walder  der  aridregion  der  Vereinigten  Staaten.  Globus,  65  :  396. 
Lorentz,  P.  G. 

1876  Vegetationsverhaltniisse  der  argentinischen  Republik.  Buenos  Aires. 
Marloth,  R. 

1887  Zur  Bedeutung  der  Salz  abscheidenden  Driisen  der  Tamariscineen. 
Ber.  Deuts.  Bot.  Gesells.  5:  319. 

Martins,  C- 

1868     Von  Spitzbergen  zur  Sahara.     Jena. 
Massart,  J. 

1898  Un  voyage  botanique  an  Sahara.  Bull.  Soc.  Roy.  Bot.  Belg.  37:  202. 
Maury,  P. 

1888  Anatomic  comparee  de  quelques  especes  caracteristiques  du  Sahara 
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Mead,  E. 

1897  The  arid  public  lands ;  their  reclamation,  management,  and  disposal. 
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Merriam,  C.  H. 

1893  Notes  on  the  distribution  of  trees  and  shrubs  in  the  deserts  and  desert 
ranges  of  southern  California,  southern  Nevada,  northwestern  Arizona, 
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1893  Notes  on  the  geographic  and  vertical 'distribution  of  cactuses,  yuccas, 
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southern  Nevada,  northwestern  Arizona,  and  southwestern  Utah.  U. 
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1898  Life  zones  and  crop  zones  of  the  United  States.  Bull.  U.  S.  Dept. 
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Mulford,  A.  I. 

1896     A  study  of  the  agaves  of  the  United  States.     Rept.  Mo.  Bot.  Gard.  7  :  47- 
Murray,  J.  M. 

1890     Meteorological  conditions  of  desert  regions  with  especial  reference  to 
the  Sahara.     Proc.  Roy.  Geog.  Soc.  August. 
Nathorst,  A.  G. 

1883     Nya    bidrag   till  kannedomen  om    Spetsbergens  karlvaxter.       Sv.  Vet. 
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1881     Einige   wissenschaftliche   Resultate    einer    argentinischen   Expedition 
nach  dem  Rio  Negro  (Patagonien).     Zeitschr.  Gesells.  Erdkunde. 
Parish,  S.  B. 

1903     A  sketch  of  the  flora  of  southern  California.     Bot.  Gaz.  36  :  203. 
Philippi,  R.  A. 

i860     Reise  durch  die  Wiiste  Atacama.     Halle. 
Pick,  H. 

1881  Beitrage  zur  Kenntnis  des  assimilierenden  Gewebes  armlaubiger  Pflan- 
zen.     (Diss.)  Bonn. 


50  DESERT  BOTANICAL  LABORATORY 

Preuss,  p. 

1901     Expedition  nach  Central-  und  Siidamerika.   1899-1900.     Berlin. 
Prschewalski,  N.  M. 

1872     Von  Kiachta  nach  Peking.     Petermann's  Mittheilungen. 

1884  Reisen  in  Tibet  und  am  oberen  Laufe  des  Gelben  Flusses.     (Deutsch 
von  Stein-Nordheim.)     Jena. 

Purpus,  C.  A. 

1899     Eine  Succulententour  in  das  Wustengebiet  des  siidlichen  Nevada,  des 

nordwestlichen  Arizona  und  des  siidwestlichen  Utah.     Monatsschrift  fiir 

Kakteenkunde,  9  :  49.  65. 
Radde,  G 

1886  Vorlaiifiger  Bericht  uber  die  Expedition  nach  Transkaspien  und  Nord- 
Chorassan  in  1886.     Petermann's  Mittheilungen. 

Rath,  G.  vom. 

1888  Arizona,  das  alte  Land  der  Indianer.     2.  Aufl. 
Redhead,  R.  M. 

1867     Notes  on  the  flora  of  the  desert  of  Sinai.     Jour.  Linn.  Soc.  Lond.  Bot. 
9  :  208. 
Ross,  H. 

1887  Beitrage  zur  Kenntnis  des  Assimilationsgewebes  und  der  Korkentwick- 
lung  armlaubiger  Ptianzen.     (Diss.)  Freiburg. 

Schenck,  A. 

1889  Das    deutsche    siidvvestafrikanische    Schutzgebiet.      Verhandl.    Gesells. 
Erdkunde  Berlin. 

1893     Gebirgsbau  und  Bodengestaltung  von  Deutsch-Sudvvest-Airika.     Ver- 
handl. des  X.  Deutschen  Geographentags.  Stuttgart. 
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1884  7  Deutsch-Siidwestafrika.     Oldenburg  und  Leipzig. 

1898  Pflanzen-Geographie  auf  Phvsiologischer  Grundlage.     Jena. 

1890  Ueber    Schutzmittel   des    Laubes    gegen  Transpiration.       Sitzungsber. 
Akad.  Berlin,  2. 

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1890     Die  deutsche  Interessensphare  in  Siidwest-Afrika.    Fernschau,  4. 
Schirmer,  H. 

1893     Le  Sahara  Paris.     (Rev.  in  Exp.  Sta.  Rec.  6:  513,  1895.) 
Schube,  T. 

1885  Beitrage  zur  Kenntnis  der  Anatomic  blattarmer  Pflanzen,  mit  beson- 
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Shinn,  C.  H,,  and  Jaffa,  M.  E. 

1899  Australian  salt-bushes.     Calif.  Ag.  Exp.  Sta.  Bull.  No.  125. 
Sitgreaves,  L. 

1854     Report  of  an  expedition  down  the  Zuni  and  Colorado  rivers.     Wash- 
ington. 
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1900  The  conquest  of  arid  America.     New  York  and  London. 
Souleyre,  A. 

1900     The  future  of    desert  cuntriis.      Rev.  Sci.  Paris,  IV.    14:    545,    681, 
743- 


BIBLIOGRAPHY 


5' 


Stansbury,  H. 

1852     Exploration  and  survey  of  the  valley  of  the  Great  Salt  Lake  of  Utah, 
including  a  reconnoissance  of  a  new  route  through  the  Rocky  moun- 
tains.    Philadelphia. 
Stapf,  0. 

1888     DerLandschaftscharakter  der  persischen  Steppen  und  Wiisten.    Oesterr.- 
Ungarische  Revue. 
Tourney,  J.  W. 

1895     Vegetal  dissemination  in  the  genus  Opuntia.     Bot.  Gaz.  20  :  356. 
1895     Ec/iinocactus  -wislizeni  and  some  related  species.      Garden  and  Forest, 
8:    154. 

1895  Opuntia  fulgida.     Garden  and  Forest,  8  :  324. 

1896  Opuntia  arborescens  in  the  Southwest.     Garden  and  Forest,  9  :  2. 

1897  The  giant  cactus.     Pop.  Sci.  Monthly,  51  :  641. 

1898  The  tree  opuntias  of  the  United  States.     Bot.  Gaz.  25  :   119. 
Townsend,  C.  H.  T. 

1895     On  the  biogeography  of  Mexico,  New  Mexico  and  Arizona.     Trans. 
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1897  On  the  biogeography  of  Mexico  and  the  southwestern  United  States. 
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Tschirch,  A. 

1881     Ueber  einige  Beziehungen  des  anatomischen  Baues  der  Assimilations- 

organe  zu  Klima  und  Standort,  etc.      Linnsea,  43  :   139. 
1895     Beitrage  zu  der  Anatomic  und   dem  EinroUungsmechanismus  einiger 
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United  States  Department  of  Interior. 

1859     Report  of  the  United  States  and  Mexican  boundary  survey.    Vol.  2,  Pt.  i. 
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1854,  62-74     Exploring  expedition,  1838-^2,  under  command  of  Chas.  Wilkes. 

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Pacific  ocean,  made  in  1S53-54,  54-55.     Washington. 
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Ives.     Washington. 
1871     United  States  geological  explorations  of  the  40th  parallel,  Clarence  King 

in  charge.     Vol.  5.     Washington. 
1878     Report  upon  United  States  geological  surveys  west  of  the  looth  merid- 
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1887     Die  Flora  der  agyptisch-arabischen  Wiiste  auf  Grundlage  anatomisch- 

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1890     Ueber  Pflanzen  mit  lackirten  Blattern.     Ber.  Dents.  Bot.  Gesell.  8  :  120. 

1898  Der  Kilimandscharo. 
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1892  Lagoa  Santa   et  Bidrag  til  den  biologiski  Plantengeografi.      Mem.  de 
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1893  Note  sur  la  biologic  et   I'anatomie  de  la  feuille  des  Vellosiacees.     Bull. 
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52  DESERT  BOTANICAL  LABORATORY 

Wiesner,  J. 

1876     Die  natui-lichen  Einrichtungen  zum  Schutze  des  Chlorophylls.     Fest- 
schrift.    Z06I.  Bot.  Gesell.  Wien. 
Wislizenus,  A. 

1848     Memoir  of  a  tour  to  northern  Mexico,  connected  with  Col.  Doniphan's 
expedition  in  1846-47.     Washington. 
Wittrock,  V.  B. 

1883     Om  snons  och  isens    flora.     Nordenskidld,   Studier  och   forskningar. 
1891     Biologiska  Ormbunkstudier.     Acta  Horti  Bergiani.     Vol.  i,  No.  8. 

GROUP    2.      CLIMATE. 

Boggs,  E.  M. 

1896  Arizona  weather.     Arizona  Exp.  Sta.  Bull.  No.  20. 
Boggs,  E.  M.,  and  Barnes,  N,  H. 

1897  Arizona  weather  and  climate.     Arizona  Exp.  Sta.  Bull.  No.  27. 
Buffum,  B,  C. 

1891  Meteorology  for  1891.     Wyoming  Ag.  Exp.  Sta.  Bull.  No.  4. 

1892  Meteorology  for  1892.     Wyoming  Ag.  Exp.  Sta.  Bull.  No.  10. 
1894     Notes  on  climate,  1893.     Wyoming  Ag.  Exp.  Sta.  Bull.  No.  17. 

Conley,  J.  D. 

1896  Meteorology  for  1895,  and  notes  on  climate  from  1891-1896.    Wyoming 
Ag.  Exp.  Sta.  Bull.  No.  27. 

Devol,  W.  S. 

1889     Meteorological  report  for  April,  May  and  June,  18S9.    Nevada  Ag.  Exp. 

Sta.  Bull.  No.  5. 
1889     Meteorological  report  for  July,  August  and  September,   1889.     Nevada 

Ag.  Exp.  Sta.  Bull.  No.  6. 
1889     Meteorological  report    for    October,  November   and   December,   1889. 

Nevada  Ag.  Exp.  Sta.  Bull.  No.  7. 

1897  Sugar  beets.     (With  an  account  of  the  climate  of  Arizona  for  1896.) 
Arizona  Exp.  Sta.  Bull.  No.  23. 

Dove,  K. 

1888  Das  Klima  des  aussertropischen  SUdafrika.     Gottingen. 
Dryden,  J. 

1897     The  climate  of  Utah.     Utah  Ag.  Exp.  Sta.  Bull.  No.  47. 
Greely,  A.  W.,  and  Glassford,  W.  A. 

1891  Report  on  the  climate  of  Arizona,  etc.,  51st  Cong.,  2d  Session.     House 
of  Rep.  Ex.  Doc.  No.  287. 

Griffin,  H.  H. 

1893  Meteorological  data  and  deductions.     N.  M.  Ag.  Exp.  Sta.  Bull.  No.  11. 
Harrington,  M.  W. 

1892  Notes  on  the  climate  and  meteorology  of  Death  Valley,  California.     U. 
S.  Dept.  Agric.  (Weather  Bureau)  Bull.  No.  i. 

Miller,  W.  M. 

1889  Meteorological  report  for  1889.     Nevada  Ag.  Exp.  Sta.  Bull.  No.  3. 
1889     Meteorological  report  for  January,  February  and  March,  1S89.     Nevada 

Ag.  Exp.  Sta.  Bull.  No.  4. 


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Moore,  W.  L. 

1896     Some  climatic  features  of  the  arid  regions.    U.  S.  Dept.  Agric.    (Weather 
Bureau). 
Ridgeway,  C.  B. 

1899  Meteorological  report  for   1898.     Wyoming  Ag.  Exp.  Sta.  9th  Annual 
Report. 

1900  Meteorological  report  for  the  year  1899.     Wyoming  Ag.  Exp.  Sta.  Re- 
port 1900. 

GROUP   3.       SOIL. 

Andouard,  A. 

1893  Les  sables  du  ddsert  de  la  Basse-Egypte.     Compt.  Rend.  117:  258. 
Briggs,  L.  J. 

1900     Salts  as  influencing  the  rate  of  evaporation  of  water  from  soils.     U.  S. 
Dept.  Agric.  Report  64  :  184. 

1900     Some  necessary  modifications  in  methods  of  mechanical  analysis  as  ap- 
plied to  alkali  soils.     U.  S.  Dept.  Agric.  Report  64  :  173. 
Briggs,  L.  J.,  and  Lapbam,  M.  H. 

1902     Capillary  studies  and  filtration  of  clay  from  soil  solutions.     U.  S.  Dept. 
Agric.  (Bureau  of  Soils)  Bull.  19. 
Buffum,  B.  C. 

1896     Alkali :  some  observations  and  experiments.     Wyoming  Ag.  Exp.  Sta. 
Bull.  No.  29. 

1899  Alkali  studies,  III.     Wyoming  Ag.  Exp.  Sta.  9th  Annual  Report. 

1900  Alfalfa  and  alkali  soils.     Wyoming  Ag.  Exp.  Sta.  Bull.  No.  43. 
Buffum,  B.  C,  and  Slosson,  E.  E. 

1900     Alkali  studies,  V.     Wyoming  Ag.  Exp.  Sta.  loth  Annual  Report. 
Cameron,  F.  K. 

1900  Application  of  the  theory  of  solutions  to  the  study  of  soils.     U.  S.  Dept. 
Agric.  Report  64:  141. 

1901  Application  of  the  theory  of   solution  to  the  study   of  soils.     U.  S. 
Dept.  Agric.  (Div.  of  Soils)  Report  2  :  423. 

1901     Soil  solutions  :   their  nature   and  functions,  and  the  classification  of 
alkali  lands.     U.  S.  Dept.  Agric.  (Div.  of  Soils)  Bull.  17. 
Cameron,  F.  K.,  Briggs,  L.  J.,  and  Seidell,  A. 

1901     Solution  studies  of  salts  occurring  in  alkali  soils.     U.  S.  Dept.  Agric. 
(Div.  of  Soils)  Bull.  18. 
Colemore,  C. 

1894  Soluble  salts  present  in  different  portions  of  an  alkali  spot.     Calif.  Ag. 
Exp.  Sta.  Report  1892-94  (in  part)  :  141. 

Collingwood,  C.  B. 

1892     Soils  and  waters.     Arizona  Exp.  Sta.  Bull.  No.  6. 
Davy,  J.  B. 

1901     Alkali  and  alkali  indicators  of  the  Gooselands.     Calif.  Ag.  Exp.  Sta. 
Report  1898-1901  :   29. 
Fireman,  P. 

1900-1     Russian   soil   investigations.     (Translated  and  condensed  from  the 
original  of  N.  Sibirtzen.)     Exp.  Sta.  Record,  12  :  704,  807. 


54  DESERT    BOTANICAL    LABORATORY 

Forbes,  R.  H. 

1895     Alkali.     Arizona  Exp.  Sta.  Bull.  No.  18. 

1898  Salt  river  valley  soils.     Arizona  Exp.  Sta.    Bull.  No.  28. 
Gardner,  F.  D.,  and  Jensen,  C.  A. 

1901     Soil  survey  in  Weber   county,   Utah.     U.   S.   Dept.  Agric.    (Div.    of 

Soils)  Report  2  :  207. 
1901     Soil  survey  in  the  Sevier  valley,  Utah.     U.  S.  Dept.  Agric.  (Div.  of 

Soils)  Report  2  :  243. 
Gardner,  F.  D.,  and  Stewart,  J. 

1899  A  soil  survey  in  Salt  Lake  valley,  Utah.  U.  S.  Dept.  Agric.  Report 
64:  77. 

1900  A  soil  survey  in  Salt  Lake  valley,  Utah.  Utah  Agric.  Exp.  Sta.  Bull. 
No.  72.     (This  is  a  reprint  of  the  preceding  report.) 

Goss,  A.,  and  Griffin,  H.  H. 

1897  Alkali  on  the  Rio  Grande  and  Animas  valleys.  N.  M.  Agric.  Exp. 
Sta.  Bull.  No.  22. 

GuUey,  F.  A. 

1893     Experimental  work  at  Willcox.     Arizona  Exp.  Sta.  Bull.  No.  10. 
Harrington,  H.  H. 

1892     Chemical  composition  of  Texas  soils.     Texas  Agric.  Exp.   Sta.  Bull. 
No.  25. 
Headen,  W.  P. 

1898  A  soil  study.     Colorado  Agric.  Exp.  Sta.  Bull.  No.  46. 
Hilgard,  E.  W. 

1876-80  Alkali  soils.  Calif.  Ag.  Exp.  Sta.  Report  1876-1877  :  43  ;  Report 
1878-1879:  30;  Report  1880:  12. 

1884  Examinations  of  tule,  marsh  and  alkali  soils.  Calif.  Agric.  Exp.  Sta. 
Bull.  No.  28. 

1885  Examinations  of  soils  and  subsoils.     Calif.  Ag.  Exp.  Sta.  Bull.  No.  36. 

1886  Irrigation,  drainage  and  alkali.     Calif.  Agric.  Exp.  Sta.  Bull.  No.  53. 
1888-9     Reports  of  examinations  of  waters,  water  supply  and  related  subjects 

s  during  the  year  1886-S9.      Calif.  Agric.  Exp.  Sta.  Report  1888-1889 
(advance  sheets). 
1890     Alkali,  alkali  soils,  their  value  and  reclamation.     Calif.  Agric.  Exp. 
Sta.  Report  1888-1889  :   139. 

1890  On  the  mutual  reactions  of  carbonates,  sulphates  and  chlorides  of  alka- 
line earth  and  alkalies.  Calif.  Ag.  Exp.  Sta.  Report  1888-1889  (ad- 
vance sheets) :  53. 

i8go  Soil  investigations  :  its  methods  and  results.  Report  1888-1889  (ap- 
pendix i)  :   151. 

1891  Alkali,  its  nature,  causes  and  repression.  Calif.  Agric.  Exp.  Sta. 
Report  1890 :  87. 

1892  Alkali  lands,  irrigation  and  drainage  in  their  mutual  relations.  Calif. 
Agric.  Exp.  Sta.  Report  1890  (appendix)  :  9. 

1892     Report  on  the  relations  of  soils  to  climate.    U.  S.  Dept.  Agric.  (Weather 

Bureau)  Bull.  No.  3. 
1894     Influence   of   climate   upon    the   formation   and   composition  of   soils. 

Calif.  Agric.  Exp.  Sta.  Report  1892-1894  (in  part)  :  100. 


BIBLIOGRAPHY  55 

Hilgard,  E.  W.  —  continued. 

1895     Fruits  and   soils  of   the  arid  region.     Calif.   State   Bd.   Hort.  Report 
1893  and  1894  :  303. 

1895  The  distribution  of  the  salts  in  alkali  soils.     Calif.  Agric.  Exp.  Sta. 
Bull.  108. 

1898     Some  physical   and   chemical   peculiarities  of   arid   soils.     Proc.  Soc. 

Prom.  Agric.  Sci. 
1900     Nature,  value  and  utilization  of  alkali  lands.   Calif.  Ag.  Exp.  Sta.  Bull. 

No.  128. 
1900     The  use  of  saline  and  alkali  waters  in   irrigation.     Calif.  Agric.  Exp. 

Sta.  Report  1897-98:  126. 
Hilgard,  E.  W.,  and  Loughridge,  R.  H. 

1896  The  distribution  of  the  salts   in  alkali  soils.     Calif.  Agric.  Exp.  Sta. 
Report  1894-95  :  37. 

1896     The  growing  of  sugar  beets  on  alkali  soil   at  Chino.     Calif.  Agric. 
Exp.  Sta.  Report  1894-95  :  71. 

1900  Endurance  of    drought   in  the  arid  region.     Calif.  Agric.  Exp.   Sta. 
Report  1897-98 :  40. 

Hilgard,  E.  W.,  and  Weber,  A.  H. 

1890     On  the  mutual  reaction  of  carbonates,  sulphates,  and  chlorides  of  the 

alkali  earths  and  alkalies.     Calif.  Agric.  Exp.  Sta.  Report  1886-1889. 

SI- 
Holmes,  J.  G. 

1901  Soil  Survey  around  Santa  Ana,  California.     U.  S.  Dept.  Agric.     (Div. 
of  Soils)  Report  2  :  385. 

Holmes,  J.  G.,  and  Mesmer,  L. 

1902  Soil    survey   of   the   Ventura   area,   California.     U.    S.J  Dept.    Agric. 
(Bureau  of  Soils)  Report  3  :  521. 

Jaffa,  M.  E. 

1892     Further  experiments  on  the  reactions  between  alkali  sulphates,  calcic 
carbonate   and  free    carbonic   acid.     Calif.    Agric.   Exp.    Sta.  Report 
1890:   100. 
Jensen,  C.  A.,  and  Olshausen,  B.  A. 

1902     Soil  survey  of   the  Yakima  area,  Washington.     U.    S.   Dept.    Agric. 
(Bureau  of  Soils)  Report  3  :  389. 
Johnson,  A.  A. 

1894     The  reclamation  of  arid  land.     Wyoming  Agric.  Exp.  Sta.  Bull.  No.  18. 

Kearney,  T.  H.,  and  Cameron,  F.  K. 

1902     Some  mutual  relations  between  alkali  soils  and  vegetation.    U.  S.  Dept. 
Agric.  (Div.  of  Soils)  Report  71. 

Knapp,  S.  A. 

1898     Occurrence  and  treatment  of  the  carbonate  of  soda  deposits  of  the  Great 
Basin.     Mg.  and  Sci.  Press,  77:  448. 
Knock,  T.  L. 

1902     Notes  on  alkali  land.     Calif.  Agric.  Exp.  Sta.  Report  189S-1901  :  27. 

Lapham,  M.  H.,and  Heileman,  W.  H. 

1902     Soil    survey   of   the    Hanford   area,    California.     U.    S.    Dept.    Agric. 
(Bureau  of  Soils)  Report  3  :  447. 


56  DESERT  BOTANICAL  LABORATORY 

igoi     Soil  survejof  the  Lower  Salinas  valley,  California.     U.  S.  Dept.  Agric. 
(Bureau  of  Soils)  Report  3  :  481. 
Loughridge,  R.  H. 
1893     Reclamation  test  with  gypsum  at  the  experiment  station  near  Tulare. 
Calif.  Agric.  Exp.  Sta.    Report  1891-92:  80. 

1893  Alkali.     Calif.  Agric.  Exp.  Sta.  Report  1891-92  :  80. 

1894  Investigations   in   soil  physics.     Calif.   Agric.   Exp.   Sta.  Report  1892- 
94  (in  part)  :  70. 

1898     Alkali  and  alkali  soils.     Calif.  Agric.  Exp.  Sta.  Report  1895-97  :  38. 
1900     Effect  of  alkali  on  citrus  trees.     Calif.  Agric.  Exp.  Sta.  Report  1897- 
98:  99. 

1900  Moisture  in  California  soils  in   1898.      Calif.  Agric.  Exp.  Sta.  Report 
1897-98:  65. 

1901  Tolerance  of  alkali  by  various  cultures.     Calif.  Agric.  Exp.  Sta.  Bull. 
No.  33. 

1902  The  gooselands  of  Glenn  and  Colusa  counties.     Calif.  Agric.  Exp.  Sta. 
Report  1898-1901  :  21. 

Mead,  C.  E. 

igoo     Notes  from  the  San  Juan  substation.     N.  M.  Agric.  Exp.  Sta.  Bull. 
No.  33. 
Means,  T.  H. 

1900     A  reconnaissance  in  the  Cache  a  la  Poudre  valley,  Colorado.     U.  S. 
Dept.  Agric.  Report  64  :  120. 

1900  A  reconnaissance  in  Sanpete,  Cache,  and  Utah  counties,  Utah.     U.  S. 
Dept.  Agric.  Report  64  ;  115. 

1901  Soil  survey  in    the  Salt  River  valley,   Arizona.     U.  S.  Dept.  Agric. 
(Div.  of  Soils)  Report  2  :  287. 

1903  Reclamation  of  alkali   lands  in   Egypt.     As  adapted  to  similar  work  in 
the  United  States.     U.  S.  Dept.  Agric.  (Bur.  of  Soils)  Bull.  No.  24. 

Means,  T.  H.,  and  Holmes,  J.  G. 

1901  Soil  survey  around  Fresno,  California.     U.  S.  Dept.  Agric.   (Div.  of 
Soils)  Report  2:  333. 

1902  Soil  survey  around  Imperial,  California.     U.  S.  Dept.  Agric.  (Div.  of 
Soils)  Report  3  :  587. 

Means,  T.  H.,  and  Gardner,  F.  D. 

1900    A  soil  survey  in  the  Pecos  valley.  New  Mexico.     U.  S.  Dept.  Agric. 
Report  64 :  36. 
Merrill,  L.  A. 

1898     Alkali  lands.     Utah  Agric.  Exp.  Sta.  Report  9  :  26. 
Ridgeway,  C.  B. 
1897     Mechanical  analysis  and  water  content  of  Wyoming  soils.     Wyoming 
Agric.  Exp.  Sta.  Bull.  No.  35. 
Shinn,  C.  H. 

1894     Reclamation  of  alkali  land  with  gypsum  at  the  Tulare  station.     Re- 
port 1892-94  (in  part)  :  145. 
1894     Reports  of  culture  work  at  the  San  Joaquin  station.     Calif.  Agric.  Exp- 
Sta.     Report  1892-1894  (in  part)  :  401. 


BIBLIOGRAPHY  57 

Shinn,  C.  H.  —  continued. 

1896  Culture  work  at  the  San  Joaquin  valley  substation.  Calif.  Agric.  Exp. 
Sta.  Report  1894-95  :  416. 

1898     Culture  work  at  the  Joaquin  valley  substation.     Calif.  Agric.  Exp.  Sta. 
Report  1895-97  :  346. 
Slosson,  E,  E. 

1898     Alkali  studies,  IV.     Wyoming  Agric.  Exp.  Sta.  Report  9. 

1900  Distribution  of  alkali  in  the  soil  of  the  experiment  farm.  Wyoming 
Agric.  Exp.  Sta.  Report  10. 

Slosson,  E,  E.,  and  Buffum,  B.  C. 

1898     Alkali  studies,  II.     Wyoming  Agric.  Exp.  Sta.  Bull.  No.  39. 
Snow,  F.  J.,  Hilgard,  E.  W.,  and  Shaw,  G.  W. 

1902     Lands  of  the  Colorado  delta  in  the   Salton  basin.     Calif.  Agric.  Exp. 
Sta.  Bull.  No.  140. 
Stewart,  J. 

1898     Effect  of  alkali  on  seed  germination.     Utah  Agric.  Exp.  Sta.  Report 
9  :  26. 
Tinsley,  J.  D. 
1902     Alkali.     N.  M.  Agric.  Exp.  Sta.  Bull.  No.  42. 

1902     Drainage  and  flooding  for  the  removal  of  alkali.     N.  M.  Agric.  Exp. 
Sta.  Bull.  No.  43. 
Tinsley,  J.  D.,  and  Vernon,  J.  J, 

1901  Soil  and  soil  moisture  investigations  for  the  season  of  1900.  N.  M. 
Agric.  Exp.  Sta.  Bull.  No.  38. 

Tolman,  T.  M. 

1902  An  investigation  of  soil  sediments  as  formed  under  arid  and  humid 
conditions  with  regard  to  their  plant-food  value.  Calif.  Agric.  Exp. 
Sta.  Report  1898-1901  :  33. 

Traphagen,  F.  W. 

i8g8     The  alkali  soils  of  Montana.     Montana  Agric.  Exp.  Sta.  Bull.  18. 
Whitney,  Milton. 

1900  Field  operations  of  the  division  of  soils  in  1899.  U.  S.  Dept.  Agric. 
Report  64 :   13. 

1901  General  review  of  the  work.  U.  S.  Dept.  Agric.  (Div.  of  Soils)  Re- 
port 2  :   19. 

Whitney,  M.  and  Means,  T.  H. 

1898  The  alkali  soils  of  the  Yellowstone  valley,  from  a  preliminary  investi- 
gation of  the  soils  near  Billings,  Montana.  U.  S.  Dept.  Agric.  (Div. 
of  Soils)  Bull.  No.  14. 

Widtsoe,  J.  A. 

1898     The  chemical  composition  of  Utah  soils,  Cache  and  Sanpete  counties. 
Utah  Agric.  Exp.  Sta.  Bull.  No.  52. 
Wilson,  N.  E. 

1897  Some  Nevada  soils.     Nevada  Agric.  Exp.  Sta.  Bull.  No.  39. 

GROUP   4.       WATER. 

CoUingwood,  C.  B. 

1891     Waters  and  water  analysis.     Arizona  Exp.  Sta.  Bull.  No.  4. 


58  DESERT  BOTANICAL  LABORATORY 

Forbes,  R.  H. 

1900     [Notes  on  irrigating  waters.]    Arizona  Exp.  Sta.  Report  ii  :  180. 
igo2     The   river  irrigating  waters  of   Arizona  —  their  character  and  effects. 
Arizona  Exp.  Sta.  Bull.  No.  44. 
Goss,  A. 

1893     The  value  of  Rio  Grande  water  for  the  purpose  of  irrigation.     N.  M. 
Agric.  Exp.  Sta.    Bull.  No.  12. 

1900  Principles  of  water  analysis  as  applied  to  New  Mexican  waters.     N.  M. 
Agric.  Exp.  Sta.  Bull.  No.  34. 

Greely,  A.  W. 

1888  Rain-fall  of  the  Pacific  Slope  and  the  western  states  and  territories.' 
GuUey,  F.  A.,  and  Collingwood,  C.  B. 

1893     Pumping  water  for  irrigation   [in   southwestern   Arizona].      Arizona 
Exp.  Sta.  Bull.  No.  II. 
Hilgard,  E.  W. 

1889  The  lakes  of  the  San  Joaquin  valley.     Calif.  Agric.  Exp.   Sta.  Bull. 
No.  82. 

Knight,  W.  C,  and  Slosson,  E.  E. 

1901  Alkali  lakes  and  deposits.     Wyoming  Agric.  Exp.  Sta.  Bull.  No.  49. 
Lahache,  — 

1899     Water  in  the  Sahara.     Rev.  Sci.  Paris,  IV.  11  :  651. 
Lippincott,  J.  B. 

1901  Storage  of  water  on   the  Gila   river.     U.    S.   Geolog.   Survey  (Water 
Supply  and  Irrig.  Papers),  No.  33  :  98. 

McClatchie,  A.  J. 

1902  Irrigation  at  the  station  farm.     Arizona  Exp.  Sta.  Bull.  No.  41. 
Powell,  J.  W. 

1890-91     (Irrigation.)     U.  S.  Geolog.  Survey.     Report  ii^,   1889-90;  Report 
12^,  1890-91. 
Ridgeway,  C.  B. 

1902     Experiments  in  evaporation.     Wyoming  Agric.  Exp.  Sta.  Bull.  No.  52. 
Slosson,  E.  £. 

1895     Water  analysis.     Wyoming  Agric.  Exp.  Sta.  Bull.  No.  24. 
Walcott,  C.  D. 

1899-1900     (Hydrography.)     U.    S.   Geolog.  Survey  Report  20^,   1808-1899; 
Report  21^ 


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